diff --git a/Makefile b/Makefile
index cb9aaf4b..35a0ff1d 100644
--- a/Makefile
+++ b/Makefile
@@ -55,7 +55,7 @@ LIBS = user32.lib gdi32.lib comctl32.lib advapi32.lib shell32.lib opengl32.lib g
 
 all: $(OBJDIR)/solvespace.exe
     @cp $(OBJDIR)/solvespace.exe .
-    solvespace t7.slvs
+    solvespace alext.slvs
 
 clean:
 	rm -f obj/*
diff --git a/constraint.cpp b/constraint.cpp
index bc12ff13..68a64586 100644
--- a/constraint.cpp
+++ b/constraint.cpp
@@ -49,16 +49,16 @@ char *Constraint::DescriptionString(void) {
 //-----------------------------------------------------------------------------
 void Constraint::DeleteAllConstraintsFor(int type, hEntity entityA, hEntity ptA)
 {
-    SS.constraint.ClearTags();
-    for(int i = 0; i < SS.constraint.n; i++) {
-        Constraint *ct = &(SS.constraint.elem[i]);
+    SK.constraint.ClearTags();
+    for(int i = 0; i < SK.constraint.n; i++) {
+        Constraint *ct = &(SK.constraint.elem[i]);
         if(ct->type != type) continue;
 
         if(ct->entityA.v != entityA.v) continue;
         if(ct->ptA.v != ptA.v) continue;
         ct->tag = 1;
     }
-    SS.constraint.RemoveTagged();
+    SK.constraint.RemoveTagged();
     // And no need to do anything special, since nothing
     // ever depends on a constraint. But do clear the
     // hover, in case the just-deleted constraint was
@@ -72,7 +72,7 @@ void Constraint::AddConstraint(Constraint *c) {
 void Constraint::AddConstraint(Constraint *c, bool rememberForUndo) {
     if(rememberForUndo) SS.UndoRemember();
 
-    SS.constraint.AddAndAssignId(c);
+    SK.constraint.AddAndAssignId(c);
 
     SS.MarkGroupDirty(c->group);
     SS.later.generateAll = true;
@@ -119,7 +119,7 @@ void Constraint::MenuConstrain(int id) {
                 c.ptB = gs.point[1];
             } else if(gs.lineSegments == 1 && gs.n == 1) {
                 c.type = PT_PT_DISTANCE;
-                Entity *e = SS.GetEntity(gs.entity[0]);
+                Entity *e = SK.GetEntity(gs.entity[0]);
                 c.ptA = e->point[0];
                 c.ptB = e->point[1];
             } else if(gs.workplanes == 1 && gs.points == 1 && gs.n == 2) {
@@ -150,8 +150,8 @@ void Constraint::MenuConstrain(int id) {
             }
             if(c.type == PT_PT_DISTANCE) {
                 Vector n = SS.GW.projRight.Cross(SS.GW.projUp);
-                Vector a = SS.GetEntity(c.ptA)->PointGetNum();
-                Vector b = SS.GetEntity(c.ptB)->PointGetNum();
+                Vector a = SK.GetEntity(c.ptA)->PointGetNum();
+                Vector b = SK.GetEntity(c.ptB)->PointGetNum();
                 c.disp.offset = n.Cross(a.Minus(b));
                 c.disp.offset = (c.disp.offset).WithMagnitude(50/SS.GW.scale);
             } else {
@@ -240,7 +240,7 @@ void Constraint::MenuConstrain(int id) {
                 c.entityB = gs.entity[1];
             } else if(gs.arcs == 1 && gs.lineSegments == 1 && gs.n == 2) {
                 c.type = EQUAL_LINE_ARC_LEN;
-                if(SS.GetEntity(gs.entity[0])->type == Entity::ARC_OF_CIRCLE) {
+                if(SK.GetEntity(gs.entity[0])->type == Entity::ARC_OF_CIRCLE) {
                     c.entityA = gs.entity[1];
                     c.entityB = gs.entity[0];
                 } else {
@@ -268,10 +268,10 @@ void Constraint::MenuConstrain(int id) {
             }
             if(c.type == EQUAL_ANGLE) {
                 // Infer the nearest supplementary angle from the sketch.
-                Vector a1 = SS.GetEntity(c.entityA)->VectorGetNum(),
-                       b1 = SS.GetEntity(c.entityB)->VectorGetNum(),
-                       a2 = SS.GetEntity(c.entityC)->VectorGetNum(),
-                       b2 = SS.GetEntity(c.entityD)->VectorGetNum();
+                Vector a1 = SK.GetEntity(c.entityA)->VectorGetNum(),
+                       b1 = SK.GetEntity(c.entityB)->VectorGetNum(),
+                       a2 = SK.GetEntity(c.entityC)->VectorGetNum(),
+                       b2 = SK.GetEntity(c.entityD)->VectorGetNum();
                 double d1 = a1.Dot(b1), d2 = a2.Dot(b2);
 
                 if(d1*d2 < 0) {
@@ -309,7 +309,7 @@ void Constraint::MenuConstrain(int id) {
                 DeleteAllConstraintsFor(PT_ON_LINE, c.entityA, c.ptA);
             } else if(gs.lineSegments == 1 && gs.workplanes == 1 && gs.n == 2) {
                 c.type = AT_MIDPOINT;
-                int i = SS.GetEntity(gs.entity[0])->IsWorkplane() ? 1 : 0;
+                int i = SK.GetEntity(gs.entity[0])->IsWorkplane() ? 1 : 0;
                 c.entityA = gs.entity[i];
                 c.entityB = gs.entity[1-i];
             } else {
@@ -336,16 +336,16 @@ void Constraint::MenuConstrain(int id) {
                                 ((gs.workplanes == 1 && gs.n == 2) ||
                                  (gs.n == 1)))
             {
-                int i = SS.GetEntity(gs.entity[0])->IsWorkplane() ? 1 : 0;
-                Entity *line = SS.GetEntity(gs.entity[i]);
+                int i = SK.GetEntity(gs.entity[0])->IsWorkplane() ? 1 : 0;
+                Entity *line = SK.GetEntity(gs.entity[i]);
                 c.entityA = gs.entity[1-i];
                 c.ptA = line->point[0];
                 c.ptB = line->point[1];
             } else if(SS.GW.LockedInWorkplane()
                         && gs.lineSegments == 2 && gs.n == 2)
             {
-                Entity *l0 = SS.GetEntity(gs.entity[0]),
-                       *l1 = SS.GetEntity(gs.entity[1]);
+                Entity *l0 = SK.GetEntity(gs.entity[0]),
+                       *l1 = SK.GetEntity(gs.entity[1]);
 
                 if((l1->group.v != SS.GW.activeGroup.v) ||
                    (l1->construction && !(l0->construction)))
@@ -384,10 +384,10 @@ void Constraint::MenuConstrain(int id) {
                           "symmetric without an explicit symmetry plane.");
                     return;
                 }
-                Vector pa = SS.GetEntity(c.ptA)->PointGetNum();
-                Vector pb = SS.GetEntity(c.ptB)->PointGetNum();
+                Vector pa = SK.GetEntity(c.ptA)->PointGetNum();
+                Vector pb = SK.GetEntity(c.ptB)->PointGetNum();
                 Vector dp = pa.Minus(pb);
-                Entity *norm = SS.GetEntity(c.workplane)->Normal();;
+                Entity *norm = SK.GetEntity(c.workplane)->Normal();;
                 Vector u = norm->NormalU(), v = norm->NormalV();
                 if(fabs(dp.Dot(u)) > fabs(dp.Dot(v))) {
                     c.type = SYMMETRIC_HORIZ;
@@ -419,7 +419,7 @@ void Constraint::MenuConstrain(int id) {
             }
             if(gs.lineSegments == 1 && gs.n == 1) {
                 c.entityA = gs.entity[0];
-                Entity *e = SS.GetEntity(c.entityA);
+                Entity *e = SK.GetEntity(c.entityA);
                 ha = e->point[0];
                 hb = e->point[1];
             } else if(gs.points == 2 && gs.n == 2) {
@@ -454,8 +454,8 @@ void Constraint::MenuConstrain(int id) {
             }
             SS.UndoRemember();
 
-            Entity *nfree = SS.GetEntity(c.entityA);
-            Entity *nref  = SS.GetEntity(c.entityB);
+            Entity *nfree = SK.GetEntity(c.entityA);
+            Entity *nref  = SK.GetEntity(c.entityB);
             if(nref->group.v == SS.GW.activeGroup.v) {
                 SWAP(Entity *, nref, nfree);
             }
@@ -485,7 +485,7 @@ void Constraint::MenuConstrain(int id) {
 
         case GraphicsWindow::MNU_OTHER_ANGLE:
             if(gs.constraints == 1 && gs.n == 0) {
-                Constraint *c = SS.GetConstraint(gs.constraint[0]);
+                Constraint *c = SK.GetConstraint(gs.constraint[0]);
                 if(c->type == ANGLE) {
                     SS.UndoRemember();
                     c->other = !(c->other);
@@ -505,10 +505,10 @@ void Constraint::MenuConstrain(int id) {
 
         case GraphicsWindow::MNU_REFERENCE:
             if(gs.constraints == 1 && gs.n == 0) {
-                Constraint *c = SS.GetConstraint(gs.constraint[0]);
+                Constraint *c = SK.GetConstraint(gs.constraint[0]);
                 if(c->HasLabel() && c->type != COMMENT) {
                     (c->reference) = !(c->reference);
-                    SS.GetGroup(c->group)->clean = false;
+                    SK.GetGroup(c->group)->clean = false;
                     SS.GenerateAll();
                     break;
                 }
@@ -531,15 +531,15 @@ void Constraint::MenuConstrain(int id) {
                 return;
             }
 
-            Entity *ea = SS.GetEntity(c.entityA), 
-                   *eb = SS.GetEntity(c.entityB);
+            Entity *ea = SK.GetEntity(c.entityA), 
+                   *eb = SK.GetEntity(c.entityB);
             if(ea->type == Entity::LINE_SEGMENT &&
                eb->type == Entity::LINE_SEGMENT)
             {
-                Vector a0 = SS.GetEntity(ea->point[0])->PointGetNum(),
-                       a1 = SS.GetEntity(ea->point[1])->PointGetNum(),
-                       b0 = SS.GetEntity(eb->point[0])->PointGetNum(),
-                       b1 = SS.GetEntity(eb->point[1])->PointGetNum();
+                Vector a0 = SK.GetEntity(ea->point[0])->PointGetNum(),
+                       a1 = SK.GetEntity(ea->point[1])->PointGetNum(),
+                       b0 = SK.GetEntity(eb->point[0])->PointGetNum(),
+                       b1 = SK.GetEntity(eb->point[1])->PointGetNum();
                 if(a0.Equals(b0) || a1.Equals(b1)) {
                     // okay, vectors should be drawn in same sense
                 } else if(a0.Equals(b1) || a1.Equals(b0)) {
@@ -560,15 +560,15 @@ void Constraint::MenuConstrain(int id) {
                 c.entityA = gs.vector[0];
                 c.entityB = gs.vector[1];
             } else if(gs.lineSegments == 1 && gs.arcs == 1 && gs.n == 2) {
-                Entity *line = SS.GetEntity(gs.entity[0]);
-                Entity *arc  = SS.GetEntity(gs.entity[1]);
+                Entity *line = SK.GetEntity(gs.entity[0]);
+                Entity *arc  = SK.GetEntity(gs.entity[1]);
                 if(line->type == Entity::ARC_OF_CIRCLE) {
                     SWAP(Entity *, line, arc);
                 }
-                Vector l0 = SS.GetEntity(line->point[0])->PointGetNum(),
-                       l1 = SS.GetEntity(line->point[1])->PointGetNum();
-                Vector a1 = SS.GetEntity(arc->point[1])->PointGetNum(),
-                       a2 = SS.GetEntity(arc->point[2])->PointGetNum();
+                Vector l0 = SK.GetEntity(line->point[0])->PointGetNum(),
+                       l1 = SK.GetEntity(line->point[1])->PointGetNum();
+                Vector a1 = SK.GetEntity(arc->point[1])->PointGetNum(),
+                       a2 = SK.GetEntity(arc->point[2])->PointGetNum();
 
                 if(l0.Equals(a1) || l1.Equals(a1)) {
                     c.other = false;
@@ -584,15 +584,15 @@ void Constraint::MenuConstrain(int id) {
                 c.entityA = arc->h;
                 c.entityB = line->h;
             } else if(gs.lineSegments == 1 && gs.cubics == 1 && gs.n == 2) {
-                Entity *line  = SS.GetEntity(gs.entity[0]);
-                Entity *cubic = SS.GetEntity(gs.entity[1]);
+                Entity *line  = SK.GetEntity(gs.entity[0]);
+                Entity *cubic = SK.GetEntity(gs.entity[1]);
                 if(line->type == Entity::CUBIC) {
                     SWAP(Entity *, line, cubic);
                 }
-                Vector l0 = SS.GetEntity(line->point[0])->PointGetNum(),
-                       l1 = SS.GetEntity(line->point[1])->PointGetNum();
-                Vector a0 = SS.GetEntity(cubic->point[0])->PointGetNum(),
-                       a3 = SS.GetEntity(cubic->point[3])->PointGetNum();
+                Vector l0 = SK.GetEntity(line->point[0])->PointGetNum(),
+                       l1 = SK.GetEntity(line->point[1])->PointGetNum();
+                Vector a0 = SK.GetEntity(cubic->point[0])->PointGetNum(),
+                       a3 = SK.GetEntity(cubic->point[3])->PointGetNum();
 
                 if(l0.Equals(a0) || l1.Equals(a0)) {
                     c.other = false;
diff --git a/constrainteq.cpp b/constrainteq.cpp
index 74b3be57..43c1f25e 100644
--- a/constrainteq.cpp
+++ b/constrainteq.cpp
@@ -33,11 +33,11 @@ Expr *ConstraintBase::VectorsParallel(int eq, ExprVector a, ExprVector b) {
 
 Expr *ConstraintBase::PointLineDistance(hEntity wrkpl, hEntity hpt, hEntity hln)
 {
-    Entity *ln = SS.GetEntity(hln);
-    Entity *a = SS.GetEntity(ln->point[0]);
-    Entity *b = SS.GetEntity(ln->point[1]);
+    Entity *ln = SK.GetEntity(hln);
+    Entity *a = SK.GetEntity(ln->point[0]);
+    Entity *b = SK.GetEntity(ln->point[1]);
 
-    Entity *p = SS.GetEntity(hpt);
+    Entity *p = SK.GetEntity(hpt);
 
     if(wrkpl.v == Entity::FREE_IN_3D.v) {
         ExprVector ep = p->PointGetExprs();
@@ -71,13 +71,13 @@ Expr *ConstraintBase::PointLineDistance(hEntity wrkpl, hEntity hpt, hEntity hln)
 Expr *ConstraintBase::PointPlaneDistance(ExprVector p, hEntity hpl) {
     ExprVector n;
     Expr *d;
-    SS.GetEntity(hpl)->WorkplaneGetPlaneExprs(&n, &d);
+    SK.GetEntity(hpl)->WorkplaneGetPlaneExprs(&n, &d);
     return (p.Dot(n))->Minus(d);
 }
 
 Expr *ConstraintBase::Distance(hEntity wrkpl, hEntity hpa, hEntity hpb) {
-    Entity *pa = SS.GetEntity(hpa);
-    Entity *pb = SS.GetEntity(hpb);
+    Entity *pa = SK.GetEntity(hpa);
+    Entity *pb = SK.GetEntity(hpb);
     if(!(pa->IsPoint() && pb->IsPoint())) oops();
 
     if(wrkpl.v == Entity::FREE_IN_3D.v) {
@@ -113,7 +113,7 @@ Expr *ConstraintBase::DirectionCosine(hEntity wrkpl,
         Expr *mags = (ae.Magnitude())->Times(be.Magnitude());
         return (ae.Dot(be))->Div(mags);
     } else {
-        Entity *w = SS.GetEntity(wrkpl);
+        Entity *w = SK.GetEntity(wrkpl);
         ExprVector u = w->Normal()->NormalExprsU();
         ExprVector v = w->Normal()->NormalExprsV();
         Expr *ua = u.Dot(ae);
@@ -130,7 +130,7 @@ Expr *ConstraintBase::DirectionCosine(hEntity wrkpl,
 ExprVector ConstraintBase::PointInThreeSpace(hEntity workplane,
                                              Expr *u, Expr *v)
 {
-    Entity *w = SS.GetEntity(workplane);
+    Entity *w = SK.GetEntity(workplane);
 
     ExprVector ub = w->Normal()->NormalExprsU();
     ExprVector vb = w->Normal()->NormalExprsV();
@@ -141,8 +141,8 @@ ExprVector ConstraintBase::PointInThreeSpace(hEntity workplane,
 
 void ConstraintBase::ModifyToSatisfy(void) {
     if(type == ANGLE) {
-        Vector a = SS.GetEntity(entityA)->VectorGetNum();
-        Vector b = SS.GetEntity(entityB)->VectorGetNum();
+        Vector a = SK.GetEntity(entityA)->VectorGetNum();
+        Vector b = SK.GetEntity(entityB)->VectorGetNum();
         if(other) a = a.ScaledBy(-1);
         if(workplane.v != Entity::FREE_IN_3D.v) {
             a = a.ProjectVectorInto(workplane);
@@ -195,14 +195,14 @@ void ConstraintBase::GenerateReal(IdList<Equation,hEquation> *l) {
             break;
 
         case PT_PLANE_DISTANCE: {
-            ExprVector pt = SS.GetEntity(ptA)->PointGetExprs();
+            ExprVector pt = SK.GetEntity(ptA)->PointGetExprs();
             AddEq(l, (PointPlaneDistance(pt, entityA))->Minus(exA), 0);
             break;
         }
 
         case PT_FACE_DISTANCE: {
-            ExprVector pt = SS.GetEntity(ptA)->PointGetExprs();
-            Entity *f = SS.GetEntity(entityA);
+            ExprVector pt = SK.GetEntity(ptA)->PointGetExprs();
+            Entity *f = SK.GetEntity(entityA);
             ExprVector p0 = f->FaceGetPointExprs();
             ExprVector n = f->FaceGetNormalExprs();
             AddEq(l, (pt.Minus(p0)).Dot(n)->Minus(exA), 0);
@@ -210,8 +210,8 @@ void ConstraintBase::GenerateReal(IdList<Equation,hEquation> *l) {
         }
 
         case EQUAL_LENGTH_LINES: {
-            Entity *a = SS.GetEntity(entityA);
-            Entity *b = SS.GetEntity(entityB);
+            Entity *a = SK.GetEntity(entityA);
+            Entity *b = SK.GetEntity(entityB);
             AddEq(l, Distance(workplane, a->point[0], a->point[1])->Minus(
                      Distance(workplane, b->point[0], b->point[1])), 0);
             break;
@@ -220,7 +220,7 @@ void ConstraintBase::GenerateReal(IdList<Equation,hEquation> *l) {
         // These work on distance squared, since the pt-line distances are
         // signed, and we want the absolute value.
         case EQ_LEN_PT_LINE_D: {
-            Entity *forLen = SS.GetEntity(entityA);
+            Entity *forLen = SK.GetEntity(entityA);
             Expr *d1 = Distance(workplane, forLen->point[0], forLen->point[1]);
             Expr *d2 = PointLineDistance(workplane, ptA, entityB);
             AddEq(l, (d1->Square())->Minus(d2->Square()), 0);
@@ -234,8 +234,8 @@ void ConstraintBase::GenerateReal(IdList<Equation,hEquation> *l) {
         }
 
         case LENGTH_RATIO: {
-            Entity *a = SS.GetEntity(entityA);
-            Entity *b = SS.GetEntity(entityB);
+            Entity *a = SK.GetEntity(entityA);
+            Entity *b = SK.GetEntity(entityB);
             Expr *la = Distance(workplane, a->point[0], a->point[1]);
             Expr *lb = Distance(workplane, b->point[0], b->point[1]);
             AddEq(l, (la->Div(lb))->Minus(exA), 0);
@@ -243,33 +243,33 @@ void ConstraintBase::GenerateReal(IdList<Equation,hEquation> *l) {
         }
 
         case DIAMETER: {
-            Entity *circle = SS.GetEntity(entityA);
+            Entity *circle = SK.GetEntity(entityA);
             Expr *r = circle->CircleGetRadiusExpr();
             AddEq(l, (r->Times(Expr::From(2)))->Minus(exA), 0);
             break;
         }
 
         case EQUAL_RADIUS: {
-            Entity *c1 = SS.GetEntity(entityA);
-            Entity *c2 = SS.GetEntity(entityB);
+            Entity *c1 = SK.GetEntity(entityA);
+            Entity *c2 = SK.GetEntity(entityB);
             AddEq(l, (c1->CircleGetRadiusExpr())->Minus(
                       c2->CircleGetRadiusExpr()), 0);
             break;
         }
 
         case EQUAL_LINE_ARC_LEN: {
-            Entity *line = SS.GetEntity(entityA),
-                   *arc  = SS.GetEntity(entityB);
+            Entity *line = SK.GetEntity(entityA),
+                   *arc  = SK.GetEntity(entityB);
 
             // Get the line length
-            ExprVector l0 = SS.GetEntity(line->point[0])->PointGetExprs(),
-                       l1 = SS.GetEntity(line->point[1])->PointGetExprs();
+            ExprVector l0 = SK.GetEntity(line->point[0])->PointGetExprs(),
+                       l1 = SK.GetEntity(line->point[1])->PointGetExprs();
             Expr *ll = (l1.Minus(l0)).Magnitude();
 
             // And get the arc radius, and the cosine of its angle
-            Entity *ao = SS.GetEntity(arc->point[0]),
-                   *as = SS.GetEntity(arc->point[1]),
-                   *af = SS.GetEntity(arc->point[2]);
+            Entity *ao = SK.GetEntity(arc->point[0]),
+                   *as = SK.GetEntity(arc->point[1]),
+                   *af = SK.GetEntity(arc->point[2]);
 
             ExprVector aos = (as->PointGetExprs()).Minus(ao->PointGetExprs()),
                        aof = (af->PointGetExprs()).Minus(ao->PointGetExprs());
@@ -301,8 +301,8 @@ void ConstraintBase::GenerateReal(IdList<Equation,hEquation> *l) {
         }
 
         case POINTS_COINCIDENT: {
-            Entity *a = SS.GetEntity(ptA);
-            Entity *b = SS.GetEntity(ptB);
+            Entity *a = SK.GetEntity(ptA);
+            Entity *b = SK.GetEntity(ptB);
             if(workplane.v == Entity::FREE_IN_3D.v) {
                 ExprVector pa = a->PointGetExprs();
                 ExprVector pb = b->PointGetExprs();
@@ -323,13 +323,13 @@ void ConstraintBase::GenerateReal(IdList<Equation,hEquation> *l) {
         case PT_IN_PLANE:
             // This one works the same, whether projected or not.
             AddEq(l, PointPlaneDistance(
-                        SS.GetEntity(ptA)->PointGetExprs(), entityA), 0);
+                        SK.GetEntity(ptA)->PointGetExprs(), entityA), 0);
             break;
 
         case PT_ON_FACE: {
             // a plane, n dot (p - p0) = 0
-            ExprVector p = SS.GetEntity(ptA)->PointGetExprs();
-            Entity *f = SS.GetEntity(entityA);
+            ExprVector p = SK.GetEntity(ptA)->PointGetExprs();
+            Entity *f = SK.GetEntity(entityA);
             ExprVector p0 = f->FaceGetPointExprs();
             ExprVector n = f->FaceGetNormalExprs();
             AddEq(l, (p.Minus(p0)).Dot(n), 0);
@@ -338,10 +338,10 @@ void ConstraintBase::GenerateReal(IdList<Equation,hEquation> *l) {
 
         case PT_ON_LINE:
             if(workplane.v == Entity::FREE_IN_3D.v) {
-                Entity *ln = SS.GetEntity(entityA);
-                Entity *a = SS.GetEntity(ln->point[0]);
-                Entity *b = SS.GetEntity(ln->point[1]);
-                Entity *p = SS.GetEntity(ptA);
+                Entity *ln = SK.GetEntity(entityA);
+                Entity *a = SK.GetEntity(ln->point[0]);
+                Entity *b = SK.GetEntity(ln->point[1]);
+                Entity *p = SK.GetEntity(ptA);
 
                 ExprVector ep = p->PointGetExprs();
                 ExprVector ea = a->PointGetExprs();
@@ -370,10 +370,10 @@ void ConstraintBase::GenerateReal(IdList<Equation,hEquation> *l) {
 
         case PT_ON_CIRCLE: {
             // This actually constrains the point to lie on the cylinder.
-            Entity *circle = SS.GetEntity(entityA);
-            ExprVector center = SS.GetEntity(circle->point[0])->PointGetExprs();
-            ExprVector pt     = SS.GetEntity(ptA)->PointGetExprs();
-            Entity *normal = SS.GetEntity(circle->normal);
+            Entity *circle = SK.GetEntity(entityA);
+            ExprVector center = SK.GetEntity(circle->point[0])->PointGetExprs();
+            ExprVector pt     = SK.GetEntity(ptA)->PointGetExprs();
+            Entity *normal = SK.GetEntity(circle->normal);
             ExprVector u = normal->NormalExprsU(),
                        v = normal->NormalExprsV();
             
@@ -389,13 +389,13 @@ void ConstraintBase::GenerateReal(IdList<Equation,hEquation> *l) {
 
         case AT_MIDPOINT:
             if(workplane.v == Entity::FREE_IN_3D.v) {
-                Entity *ln = SS.GetEntity(entityA);
-                ExprVector a = SS.GetEntity(ln->point[0])->PointGetExprs();
-                ExprVector b = SS.GetEntity(ln->point[1])->PointGetExprs();
+                Entity *ln = SK.GetEntity(entityA);
+                ExprVector a = SK.GetEntity(ln->point[0])->PointGetExprs();
+                ExprVector b = SK.GetEntity(ln->point[1])->PointGetExprs();
                 ExprVector m = (a.Plus(b)).ScaledBy(Expr::From(0.5));
 
                 if(ptA.v) {
-                    ExprVector p = SS.GetEntity(ptA)->PointGetExprs();
+                    ExprVector p = SK.GetEntity(ptA)->PointGetExprs();
                     AddEq(l, (m.x)->Minus(p.x), 0);
                     AddEq(l, (m.y)->Minus(p.y), 1);
                     AddEq(l, (m.z)->Minus(p.z), 2);
@@ -403,9 +403,9 @@ void ConstraintBase::GenerateReal(IdList<Equation,hEquation> *l) {
                     AddEq(l, PointPlaneDistance(m, entityB), 0);
                 }
             } else {
-                Entity *ln = SS.GetEntity(entityA);
-                Entity *a = SS.GetEntity(ln->point[0]);
-                Entity *b = SS.GetEntity(ln->point[1]);
+                Entity *ln = SK.GetEntity(entityA);
+                Entity *a = SK.GetEntity(ln->point[0]);
+                Entity *b = SK.GetEntity(ln->point[1]);
                 
                 Expr *au, *av, *bu, *bv;
                 a->PointGetExprsInWorkplane(workplane, &au, &av);
@@ -414,7 +414,7 @@ void ConstraintBase::GenerateReal(IdList<Equation,hEquation> *l) {
                 Expr *mv = Expr::From(0.5)->Times(av->Plus(bv));
 
                 if(ptA.v) {
-                    Entity *p = SS.GetEntity(ptA);
+                    Entity *p = SK.GetEntity(ptA);
                     Expr *pu, *pv;
                     p->PointGetExprsInWorkplane(workplane, &pu, &pv);
                     AddEq(l, pu->Minus(mu), 0);
@@ -428,9 +428,9 @@ void ConstraintBase::GenerateReal(IdList<Equation,hEquation> *l) {
 
         case SYMMETRIC:
             if(workplane.v == Entity::FREE_IN_3D.v) {
-                Entity *plane = SS.GetEntity(entityA);
-                Entity *ea = SS.GetEntity(ptA);
-                Entity *eb = SS.GetEntity(ptB);
+                Entity *plane = SK.GetEntity(entityA);
+                Entity *ea = SK.GetEntity(ptA);
+                Entity *eb = SK.GetEntity(ptB);
                 ExprVector a = ea->PointGetExprs();
                 ExprVector b = eb->PointGetExprs();
 
@@ -447,9 +447,9 @@ void ConstraintBase::GenerateReal(IdList<Equation,hEquation> *l) {
                 AddEq(l, au->Minus(bu), 1);
                 AddEq(l, av->Minus(bv), 2);
             } else {
-                Entity *plane = SS.GetEntity(entityA);
-                Entity *a = SS.GetEntity(ptA);
-                Entity *b = SS.GetEntity(ptB);
+                Entity *plane = SK.GetEntity(entityA);
+                Entity *a = SK.GetEntity(ptA);
+                Entity *b = SK.GetEntity(ptB);
 
                 Expr *au, *av, *bu, *bv;
                 a->PointGetExprsInWorkplane(workplane, &au, &av);
@@ -464,7 +464,7 @@ void ConstraintBase::GenerateReal(IdList<Equation,hEquation> *l) {
                 // to the symmetry pane's normal (i.e., that lies in the
                 // plane of symmetry). The line connecting the points is
                 // perpendicular to that constructed vector.
-                Entity *w = SS.GetEntity(workplane);
+                Entity *w = SK.GetEntity(workplane);
                 ExprVector u = w->Normal()->NormalExprsU();
                 ExprVector v = w->Normal()->NormalExprsV();
 
@@ -479,8 +479,8 @@ void ConstraintBase::GenerateReal(IdList<Equation,hEquation> *l) {
 
         case SYMMETRIC_HORIZ:
         case SYMMETRIC_VERT: {
-            Entity *a = SS.GetEntity(ptA);
-            Entity *b = SS.GetEntity(ptB);
+            Entity *a = SK.GetEntity(ptA);
+            Entity *b = SK.GetEntity(ptB);
 
             Expr *au, *av, *bu, *bv;
             a->PointGetExprsInWorkplane(workplane, &au, &av);
@@ -497,16 +497,16 @@ void ConstraintBase::GenerateReal(IdList<Equation,hEquation> *l) {
         }
 
         case SYMMETRIC_LINE: {
-            Entity *pa = SS.GetEntity(ptA);
-            Entity *pb = SS.GetEntity(ptB);
+            Entity *pa = SK.GetEntity(ptA);
+            Entity *pb = SK.GetEntity(ptB);
 
             Expr *pau, *pav, *pbu, *pbv;
             pa->PointGetExprsInWorkplane(workplane, &pau, &pav);
             pb->PointGetExprsInWorkplane(workplane, &pbu, &pbv);
 
-            Entity *ln = SS.GetEntity(entityA);
-            Entity *la = SS.GetEntity(ln->point[0]);
-            Entity *lb = SS.GetEntity(ln->point[1]);
+            Entity *ln = SK.GetEntity(entityA);
+            Entity *la = SK.GetEntity(ln->point[0]);
+            Entity *lb = SK.GetEntity(ln->point[1]);
             Expr *lau, *lav, *lbu, *lbv;
             la->PointGetExprsInWorkplane(workplane, &lau, &lav);
             lb->PointGetExprsInWorkplane(workplane, &lbu, &lbv);
@@ -533,15 +533,15 @@ void ConstraintBase::GenerateReal(IdList<Equation,hEquation> *l) {
         case VERTICAL: {
             hEntity ha, hb;
             if(entityA.v) {
-                Entity *e = SS.GetEntity(entityA);
+                Entity *e = SK.GetEntity(entityA);
                 ha = e->point[0];
                 hb = e->point[1];
             } else {
                 ha = ptA;
                 hb = ptB;
             }
-            Entity *a = SS.GetEntity(ha);
-            Entity *b = SS.GetEntity(hb);
+            Entity *a = SK.GetEntity(ha);
+            Entity *b = SK.GetEntity(hb);
 
             Expr *au, *av, *bu, *bv;
             a->PointGetExprsInWorkplane(workplane, &au, &av);
@@ -552,8 +552,8 @@ void ConstraintBase::GenerateReal(IdList<Equation,hEquation> *l) {
         }
 
         case SAME_ORIENTATION: {
-            Entity *a = SS.GetEntity(entityA);
-            Entity *b = SS.GetEntity(entityB);
+            Entity *a = SK.GetEntity(entityA);
+            Entity *b = SK.GetEntity(entityB);
             if(b->group.v != group.v) {
                 SWAP(Entity *, a, b);
             }
@@ -581,8 +581,8 @@ void ConstraintBase::GenerateReal(IdList<Equation,hEquation> *l) {
 
         case PERPENDICULAR:
         case ANGLE: {
-            Entity *a = SS.GetEntity(entityA);
-            Entity *b = SS.GetEntity(entityB);
+            Entity *a = SK.GetEntity(entityA);
+            Entity *b = SK.GetEntity(entityB);
             ExprVector ae = a->VectorGetExprs();
             ExprVector be = b->VectorGetExprs();
             if(other) ae = ae.ScaledBy(Expr::From(-1));
@@ -602,10 +602,10 @@ void ConstraintBase::GenerateReal(IdList<Equation,hEquation> *l) {
         }
 
         case EQUAL_ANGLE: {
-            Entity *a = SS.GetEntity(entityA);
-            Entity *b = SS.GetEntity(entityB);
-            Entity *c = SS.GetEntity(entityC);
-            Entity *d = SS.GetEntity(entityD);
+            Entity *a = SK.GetEntity(entityA);
+            Entity *b = SK.GetEntity(entityB);
+            Entity *c = SK.GetEntity(entityC);
+            Entity *d = SK.GetEntity(entityD);
             ExprVector ae = a->VectorGetExprs();
             ExprVector be = b->VectorGetExprs();
             ExprVector ce = c->VectorGetExprs();
@@ -621,12 +621,12 @@ void ConstraintBase::GenerateReal(IdList<Equation,hEquation> *l) {
         }
 
         case ARC_LINE_TANGENT: {
-            Entity *arc  = SS.GetEntity(entityA);
-            Entity *line = SS.GetEntity(entityB);
+            Entity *arc  = SK.GetEntity(entityA);
+            Entity *line = SK.GetEntity(entityB);
 
-            ExprVector ac = SS.GetEntity(arc->point[0])->PointGetExprs();
+            ExprVector ac = SK.GetEntity(arc->point[0])->PointGetExprs();
             ExprVector ap = 
-                SS.GetEntity(arc->point[other ? 2 : 1])->PointGetExprs();
+                SK.GetEntity(arc->point[other ? 2 : 1])->PointGetExprs();
 
             ExprVector ld = line->VectorGetExprs();
 
@@ -636,13 +636,13 @@ void ConstraintBase::GenerateReal(IdList<Equation,hEquation> *l) {
         }
 
         case CUBIC_LINE_TANGENT: {
-            Entity *cubic = SS.GetEntity(entityA);
-            Entity *line  = SS.GetEntity(entityB);
+            Entity *cubic = SK.GetEntity(entityA);
+            Entity *line  = SK.GetEntity(entityB);
             
             ExprVector endpoint =
-                SS.GetEntity(cubic->point[other ? 3 : 0])->PointGetExprs();
+                SK.GetEntity(cubic->point[other ? 3 : 0])->PointGetExprs();
             ExprVector ctrlpoint = 
-                SS.GetEntity(cubic->point[other ? 2 : 1])->PointGetExprs();
+                SK.GetEntity(cubic->point[other ? 2 : 1])->PointGetExprs();
             
             ExprVector a = endpoint.Minus(ctrlpoint);
 
@@ -652,7 +652,7 @@ void ConstraintBase::GenerateReal(IdList<Equation,hEquation> *l) {
                 AddEq(l, VectorsParallel(0, a, b), 0);
                 AddEq(l, VectorsParallel(1, a, b), 1);
             } else {
-                Entity *w = SS.GetEntity(workplane);
+                Entity *w = SK.GetEntity(workplane);
                 ExprVector wn = w->Normal()->NormalExprsN();
                 AddEq(l, (a.Cross(b)).Dot(wn), 0);
             }
@@ -660,7 +660,7 @@ void ConstraintBase::GenerateReal(IdList<Equation,hEquation> *l) {
         }
 
         case PARALLEL: {
-            Entity *ea = SS.GetEntity(entityA), *eb = SS.GetEntity(entityB);
+            Entity *ea = SK.GetEntity(entityA), *eb = SK.GetEntity(entityB);
             if(eb->group.v != group.v) {
                 SWAP(Entity *, ea, eb);
             }
@@ -671,7 +671,7 @@ void ConstraintBase::GenerateReal(IdList<Equation,hEquation> *l) {
                 AddEq(l, VectorsParallel(0, a, b), 0);
                 AddEq(l, VectorsParallel(1, a, b), 1);
             } else {
-                Entity *w = SS.GetEntity(workplane);
+                Entity *w = SK.GetEntity(workplane);
                 ExprVector wn = w->Normal()->NormalExprsN();
                 AddEq(l, (a.Cross(b)).Dot(wn), 0);
             }
diff --git a/draw.cpp b/draw.cpp
index dc9a5529..ebd31156 100644
--- a/draw.cpp
+++ b/draw.cpp
@@ -1,7 +1,7 @@
 #include "solvespace.h"
 
 void GraphicsWindow::UpdateDraggedPoint(hEntity hp, double mx, double my) {
-    Entity *p = SS.GetEntity(hp);
+    Entity *p = SK.GetEntity(hp);
     Vector pos = p->PointGetNum();
     UpdateDraggedNum(&pos, mx, my);
     p->PointForceTo(pos);
@@ -80,7 +80,7 @@ void GraphicsWindow::MouseMoved(double x, double y, bool leftDown,
         // start dragging something.
         if(leftDown && dm > 3) {
             if(hover.entity.v) {
-                Entity *e = SS.GetEntity(hover.entity);
+                Entity *e = SK.GetEntity(hover.entity);
                 if(e->IsPoint()) {
                     // Start dragging this point.
                     ClearSelection();
@@ -97,7 +97,7 @@ void GraphicsWindow::MouseMoved(double x, double y, bool leftDown,
                     pending.operation = DRAGGING_NORMAL;
                 }
             } else if(hover.constraint.v && 
-                            SS.GetConstraint(hover.constraint)->HasLabel())
+                            SK.GetConstraint(hover.constraint)->HasLabel())
             {
                 ClearSelection();
                 pending.constraint = hover.constraint;
@@ -132,7 +132,7 @@ void GraphicsWindow::MouseMoved(double x, double y, bool leftDown,
     if(!havePainted) return;
     switch(pending.operation) {
         case DRAGGING_CONSTRAINT: {
-            Constraint *c = SS.constraint.FindById(pending.constraint);
+            Constraint *c = SK.constraint.FindById(pending.constraint);
             UpdateDraggedNum(&(c->disp.offset), x, y);
             break;
         }
@@ -141,7 +141,7 @@ void GraphicsWindow::MouseMoved(double x, double y, bool leftDown,
             // and fall through
         case DRAGGING_NEW_POINT:
         case DRAGGING_POINT: {
-            Entity *p = SS.GetEntity(pending.point);
+            Entity *p = SK.GetEntity(pending.point);
             if((p->type == Entity::POINT_N_ROT_TRANS) &&
                (shiftDown || ctrlDown))
             {
@@ -194,12 +194,12 @@ void GraphicsWindow::MouseMoved(double x, double y, bool leftDown,
             HitTestMakeSelection(mp);
 
             hRequest hr = pending.point.request();
-            Vector p0 = SS.GetEntity(hr.entity(1))->PointGetNum();
-            Vector p3 = SS.GetEntity(hr.entity(4))->PointGetNum();
+            Vector p0 = SK.GetEntity(hr.entity(1))->PointGetNum();
+            Vector p3 = SK.GetEntity(hr.entity(4))->PointGetNum();
             Vector p1 = p0.ScaledBy(2.0/3).Plus(p3.ScaledBy(1.0/3));
-            SS.GetEntity(hr.entity(2))->PointForceTo(p1);
+            SK.GetEntity(hr.entity(2))->PointForceTo(p1);
             Vector p2 = p0.ScaledBy(1.0/3).Plus(p3.ScaledBy(2.0/3));
-            SS.GetEntity(hr.entity(3))->PointForceTo(p2);
+            SK.GetEntity(hr.entity(3))->PointForceTo(p2);
 
             SS.MarkGroupDirtyByEntity(pending.point);
             break;
@@ -209,30 +209,30 @@ void GraphicsWindow::MouseMoved(double x, double y, bool leftDown,
             HitTestMakeSelection(mp);
 
             hRequest hr = pending.point.request();
-            Vector ona = SS.GetEntity(hr.entity(2))->PointGetNum();
-            Vector onb = SS.GetEntity(hr.entity(3))->PointGetNum();
+            Vector ona = SK.GetEntity(hr.entity(2))->PointGetNum();
+            Vector onb = SK.GetEntity(hr.entity(3))->PointGetNum();
             Vector center = (ona.Plus(onb)).ScaledBy(0.5);
 
-            SS.GetEntity(hr.entity(1))->PointForceTo(center);
+            SK.GetEntity(hr.entity(1))->PointForceTo(center);
 
             SS.MarkGroupDirtyByEntity(pending.point);
             break;
         }
         case DRAGGING_NEW_RADIUS:
         case DRAGGING_RADIUS: {
-            Entity *circle = SS.GetEntity(pending.circle);
-            Vector center = SS.GetEntity(circle->point[0])->PointGetNum();
+            Entity *circle = SK.GetEntity(pending.circle);
+            Vector center = SK.GetEntity(circle->point[0])->PointGetNum();
             Point2d c2 = ProjectPoint(center);
             double r = c2.DistanceTo(mp)/scale;
-            SS.GetEntity(circle->distance)->DistanceForceTo(r);
+            SK.GetEntity(circle->distance)->DistanceForceTo(r);
 
             SS.MarkGroupDirtyByEntity(pending.circle);
             break;
         }
 
         case DRAGGING_NORMAL: {
-            Entity *normal = SS.GetEntity(pending.normal);
-            Vector p = SS.GetEntity(normal->point[0])->PointGetNum();
+            Entity *normal = SK.GetEntity(pending.normal);
+            Vector p = SK.GetEntity(normal->point[0])->PointGetNum();
             Point2d p2 = ProjectPoint(p);
 
             Quaternion q = normal->NormalGetNum();
@@ -299,7 +299,7 @@ hRequest GraphicsWindow::AddRequest(int type, bool rememberForUndo) {
     Request r;
     memset(&r, 0, sizeof(r));
     r.group = activeGroup;
-    Group *g = SS.GetGroup(activeGroup);
+    Group *g = SK.GetGroup(activeGroup);
     if(g->type == Group::DRAWING_3D || g->type == Group::DRAWING_WORKPLANE) {
         r.construction = false;
     } else {
@@ -307,7 +307,7 @@ hRequest GraphicsWindow::AddRequest(int type, bool rememberForUndo) {
     }
     r.workplane = ActiveWorkplane();
     r.type = type;
-    SS.request.AddAndAssignId(&r);
+    SK.request.AddAndAssignId(&r);
 
     // We must regenerate the parameters, so that the code that tries to
     // place this request's entities where the mouse is can do so. But
@@ -321,7 +321,7 @@ hRequest GraphicsWindow::AddRequest(int type, bool rememberForUndo) {
 bool GraphicsWindow::ConstrainPointByHovered(hEntity pt) {
     if(!hover.entity.v) return false;
 
-    Entity *e = SS.GetEntity(hover.entity);
+    Entity *e = SK.GetEntity(hover.entity);
     if(e->IsPoint()) {
         Constraint::ConstrainCoincident(e->h, pt);
         return true;
@@ -362,7 +362,7 @@ void GraphicsWindow::MouseLeftDown(double mx, double my) {
     switch(pending.operation) {
         case MNU_DATUM_POINT:
             hr = AddRequest(Request::DATUM_POINT);
-            SS.GetEntity(hr.entity(0))->PointForceTo(v);
+            SK.GetEntity(hr.entity(0))->PointForceTo(v);
             ConstrainPointByHovered(hr.entity(0));
 
             ClearSuper();
@@ -372,7 +372,7 @@ void GraphicsWindow::MouseLeftDown(double mx, double my) {
 
         case MNU_LINE_SEGMENT:
             hr = AddRequest(Request::LINE_SEGMENT);
-            SS.GetEntity(hr.entity(1))->PointForceTo(v);
+            SK.GetEntity(hr.entity(1))->PointForceTo(v);
             ConstrainPointByHovered(hr.entity(1));
 
             ClearSuper();
@@ -380,7 +380,7 @@ void GraphicsWindow::MouseLeftDown(double mx, double my) {
             pending.operation = DRAGGING_NEW_LINE_POINT;
             pending.point = hr.entity(2);
             pending.description = "click to place next point of line";
-            SS.GetEntity(pending.point)->PointForceTo(v);
+            SK.GetEntity(pending.point)->PointForceTo(v);
             break;
 
         case MNU_RECTANGLE: {
@@ -398,8 +398,8 @@ void GraphicsWindow::MouseLeftDown(double mx, double my) {
             for(i = 0; i < 4; i++) {
                 Constraint::ConstrainCoincident(
                     lns[i].entity(1), lns[(i+1)%4].entity(2));
-                SS.GetEntity(lns[i].entity(1))->PointForceTo(v);
-                SS.GetEntity(lns[i].entity(2))->PointForceTo(v);
+                SK.GetEntity(lns[i].entity(1))->PointForceTo(v);
+                SK.GetEntity(lns[i].entity(2))->PointForceTo(v);
             }
             for(i = 0; i < 4; i++) {
                 Constraint::Constrain(
@@ -416,8 +416,8 @@ void GraphicsWindow::MouseLeftDown(double mx, double my) {
         }
         case MNU_CIRCLE:
             hr = AddRequest(Request::CIRCLE);
-            SS.GetEntity(hr.entity(1))->PointForceTo(v);
-            SS.GetEntity(hr.entity(32))->NormalForceTo(
+            SK.GetEntity(hr.entity(1))->PointForceTo(v);
+            SK.GetEntity(hr.entity(32))->NormalForceTo(
                 Quaternion::From(SS.GW.projRight, SS.GW.projUp));
             ConstrainPointByHovered(hr.entity(1));
 
@@ -426,7 +426,7 @@ void GraphicsWindow::MouseLeftDown(double mx, double my) {
             pending.operation = DRAGGING_NEW_RADIUS;
             pending.circle = hr.entity(0);
             pending.description = "click to set radius";
-            SS.GetParam(hr.param(0))->val = 0;
+            SK.GetParam(hr.param(0))->val = 0;
             break;
 
         case MNU_ARC: {
@@ -439,9 +439,9 @@ void GraphicsWindow::MouseLeftDown(double mx, double my) {
             // This fudge factor stops us from immediately failing to solve
             // because of the arc's implicit (equal radius) tangent.
             Vector adj = SS.GW.projRight.WithMagnitude(2/SS.GW.scale);
-            SS.GetEntity(hr.entity(1))->PointForceTo(v.Minus(adj));
-            SS.GetEntity(hr.entity(2))->PointForceTo(v);
-            SS.GetEntity(hr.entity(3))->PointForceTo(v);
+            SK.GetEntity(hr.entity(1))->PointForceTo(v.Minus(adj));
+            SK.GetEntity(hr.entity(2))->PointForceTo(v);
+            SK.GetEntity(hr.entity(3))->PointForceTo(v);
             ConstrainPointByHovered(hr.entity(2));
 
             ClearSuper();
@@ -453,10 +453,10 @@ void GraphicsWindow::MouseLeftDown(double mx, double my) {
         }
         case MNU_CUBIC:
             hr = AddRequest(Request::CUBIC);
-            SS.GetEntity(hr.entity(1))->PointForceTo(v);
-            SS.GetEntity(hr.entity(2))->PointForceTo(v);
-            SS.GetEntity(hr.entity(3))->PointForceTo(v);
-            SS.GetEntity(hr.entity(4))->PointForceTo(v);
+            SK.GetEntity(hr.entity(1))->PointForceTo(v);
+            SK.GetEntity(hr.entity(2))->PointForceTo(v);
+            SK.GetEntity(hr.entity(3))->PointForceTo(v);
+            SK.GetEntity(hr.entity(4))->PointForceTo(v);
             ConstrainPointByHovered(hr.entity(1));
 
             ClearSuper();
@@ -474,8 +474,8 @@ void GraphicsWindow::MouseLeftDown(double mx, double my) {
                 break;
             }
             hr = AddRequest(Request::WORKPLANE);
-            SS.GetEntity(hr.entity(1))->PointForceTo(v);
-            SS.GetEntity(hr.entity(32))->NormalForceTo( 
+            SK.GetEntity(hr.entity(1))->PointForceTo(v);
+            SK.GetEntity(hr.entity(32))->NormalForceTo( 
                 Quaternion::From(SS.GW.projRight, SS.GW.projUp));
             ConstrainPointByHovered(hr.entity(1));
 
@@ -489,12 +489,12 @@ void GraphicsWindow::MouseLeftDown(double mx, double my) {
                 break;
             }
             hr = AddRequest(Request::TTF_TEXT);
-            Request *r = SS.GetRequest(hr);
+            Request *r = SK.GetRequest(hr);
             r->str.strcpy("Abc");
             r->font.strcpy("arial.ttf");
 
-            SS.GetEntity(hr.entity(1))->PointForceTo(v);
-            SS.GetEntity(hr.entity(2))->PointForceTo(v);
+            SK.GetEntity(hr.entity(1))->PointForceTo(v);
+            SK.GetEntity(hr.entity(2))->PointForceTo(v);
 
             pending.operation = DRAGGING_NEW_POINT;
             pending.point = hr.entity(2);
@@ -521,8 +521,8 @@ void GraphicsWindow::MouseLeftDown(double mx, double my) {
             }
             // Create a new line segment, so that we continue drawing.
             hRequest hr = AddRequest(Request::LINE_SEGMENT);
-            SS.GetEntity(hr.entity(1))->PointForceTo(v);
-            SS.GetEntity(hr.entity(2))->PointForceTo(v);
+            SK.GetEntity(hr.entity(1))->PointForceTo(v);
+            SK.GetEntity(hr.entity(2))->PointForceTo(v);
 
             // Constrain the line segments to share an endpoint
             Constraint::ConstrainCoincident(pending.point, hr.entity(1));
@@ -552,13 +552,13 @@ void GraphicsWindow::MouseLeftDown(double mx, double my) {
             }
             if(i != MAX_SELECTED) break;
 
-            if(hover.entity.v != 0 && SS.GetEntity(hover.entity)->IsFace()) {
+            if(hover.entity.v != 0 && SK.GetEntity(hover.entity)->IsFace()) {
                 // In the interest of speed for the triangle drawing code,
                 // only two faces may be selected at a time.
                 int c = 0;
                 for(i = 0; i < MAX_SELECTED; i++) {
                     hEntity he = selection[i].entity;
-                    if(he.v != 0 && SS.GetEntity(he)->IsFace()) {
+                    if(he.v != 0 && SK.GetEntity(he)->IsFace()) {
                         c++;
                         if(c >= 2) selection[i].Clear();
                     }
@@ -601,7 +601,7 @@ void GraphicsWindow::MouseLeftDoubleClick(double mx, double my) {
         constraintBeingEdited = hover.constraint;
         ClearSuper();
 
-        Constraint *c = SS.GetConstraint(constraintBeingEdited);
+        Constraint *c = SK.GetConstraint(constraintBeingEdited);
         if(c->reference) {
             // Not meaningful to edit a reference dimension
             return;
@@ -631,7 +631,7 @@ void GraphicsWindow::MouseLeftDoubleClick(double mx, double my) {
 
 void GraphicsWindow::EditControlDone(char *s) {
     HideGraphicsEditControl();
-    Constraint *c = SS.GetConstraint(constraintBeingEdited);
+    Constraint *c = SK.GetConstraint(constraintBeingEdited);
 
     if(c->type == Constraint::COMMENT) {
         SS.UndoRemember();
@@ -728,13 +728,13 @@ void GraphicsWindow::Selection::Draw(void) {
     Vector refp;
     if(entity.v) {
         glLineWidth(1.5);
-        Entity *e = SS.GetEntity(entity);
+        Entity *e = SK.GetEntity(entity);
         e->Draw();
         if(emphasized) refp = e->GetReferencePos();
         glLineWidth(1);
     }
     if(constraint.v) {
-        Constraint *c = SS.GetConstraint(constraint);
+        Constraint *c = SK.GetConstraint(constraint);
         c->Draw();
         if(emphasized) refp = c->GetReferencePos();
     }
@@ -766,11 +766,11 @@ void GraphicsWindow::ClearNonexistentSelectionItems(void) {
     bool change = false;
     for(int i = 0; i < MAX_SELECTED; i++) {
         Selection *s = &(selection[i]);
-        if(s->constraint.v && !(SS.constraint.FindByIdNoOops(s->constraint))) {
+        if(s->constraint.v && !(SK.constraint.FindByIdNoOops(s->constraint))) {
             s->constraint.v = 0;
             change = true;
         }
-        if(s->entity.v && !(SS.entity.FindByIdNoOops(s->entity))) {
+        if(s->entity.v && !(SK.entity.FindByIdNoOops(s->entity))) {
             s->entity.v = 0;
             change = true;
         }
@@ -786,7 +786,7 @@ void GraphicsWindow::GroupSelection(void) {
         if(s->entity.v) {
             (gs.n)++;
 
-            Entity *e = SS.entity.FindById(s->entity);
+            Entity *e = SK.entity.FindById(s->entity);
             // A list of points, and a list of all entities that aren't points.
             if(e->IsPoint()) {
                 gs.point[(gs.points)++] = s->entity;
@@ -841,8 +841,8 @@ void GraphicsWindow::HitTestMakeSelection(Point2d mp) {
 
     // Always do the entities; we might be dragging something that should
     // be auto-constrained, and we need the hover for that.
-    for(i = 0; i < SS.entity.n; i++) {
-        Entity *e = &(SS.entity.elem[i]);
+    for(i = 0; i < SK.entity.n; i++) {
+        Entity *e = &(SK.entity.elem[i]);
         // Don't hover whatever's being dragged.
         if(e->h.request().v == pending.point.request().v) continue;
 
@@ -857,18 +857,18 @@ void GraphicsWindow::HitTestMakeSelection(Point2d mp) {
     // The constraints and faces happen only when nothing's in progress.
     if(pending.operation == 0) {
         // Constraints
-        for(i = 0; i < SS.constraint.n; i++) {
-            d = SS.constraint.elem[i].GetDistance(mp);
+        for(i = 0; i < SK.constraint.n; i++) {
+            d = SK.constraint.elem[i].GetDistance(mp);
             if(d < 10 && d < dmin) {
                 memset(&s, 0, sizeof(s));
-                s.constraint = SS.constraint.elem[i].h;
+                s.constraint = SK.constraint.elem[i].h;
                 dmin = d;
             }
         }
 
         // Faces, from the triangle mesh; these are lowest priority
         if(s.constraint.v == 0 && s.entity.v == 0 && showShaded && showFaces) {
-            SMesh *m = &((SS.GetGroup(activeGroup))->runningMesh);
+            SMesh *m = &((SK.GetGroup(activeGroup))->runningMesh);
             DWORD v = m->FirstIntersectionWith(mp);
             if(v) {
                 s.entity.v = v;
@@ -1001,7 +1001,7 @@ void GraphicsWindow::Paint(int w, int h) {
 
     // Draw the active group; this fills the polygons in a drawing group, and
     // draws the solid mesh.
-    (SS.GetGroup(activeGroup))->Draw();
+    (SK.GetGroup(activeGroup))->Draw();
 
     // Now draw the entities
     if(showHdnLines) glDisable(GL_DEPTH_TEST);
@@ -1009,8 +1009,8 @@ void GraphicsWindow::Paint(int w, int h) {
 
     glDisable(GL_DEPTH_TEST);
     // Draw the constraints
-    for(i = 0; i < SS.constraint.n; i++) {
-        SS.constraint.elem[i].Draw();
+    for(i = 0; i < SK.constraint.n; i++) {
+        SK.constraint.elem[i].Draw();
     }
 
     // Draw the traced path, if one exists
diff --git a/drawconstraint.cpp b/drawconstraint.cpp
index b6017d6b..16967e59 100644
--- a/drawconstraint.cpp
+++ b/drawconstraint.cpp
@@ -105,9 +105,9 @@ void Constraint::DoEqualLenTicks(Vector a, Vector b, Vector gn) {
 }
 
 void Constraint::DoEqualRadiusTicks(hEntity he) {
-    Entity *circ = SS.GetEntity(he);
+    Entity *circ = SK.GetEntity(he);
 
-    Vector center = SS.GetEntity(circ->point[0])->PointGetNum();
+    Vector center = SK.GetEntity(circ->point[0])->PointGetNum();
     double r = circ->CircleGetRadiusNum();
     Quaternion q = circ->Normal()->NormalGetNum();
     Vector u = q.RotationU(), v = q.RotationV();
@@ -194,7 +194,7 @@ void Constraint::DoArcForAngle(Vector a0, Vector da, Vector b0, Vector db,
 
 void Constraint::DrawOrGetDistance(Vector *labelPos) {
     if(!SS.GW.showConstraints) return;
-    Group *g = SS.GetGroup(group);
+    Group *g = SK.GetGroup(group);
     // If the group is hidden, then the constraints are hidden and not
     // able to be selected.
     if(!(g->visible)) return;
@@ -210,8 +210,8 @@ void Constraint::DrawOrGetDistance(Vector *labelPos) {
     glxColor3d(1, 0.1, 1);
     switch(type) {
         case PT_PT_DISTANCE: {
-            Vector ap = SS.GetEntity(ptA)->PointGetNum();
-            Vector bp = SS.GetEntity(ptB)->PointGetNum();
+            Vector ap = SK.GetEntity(ptA)->PointGetNum();
+            Vector bp = SK.GetEntity(ptB)->PointGetNum();
 
             if(workplane.v != Entity::FREE_IN_3D.v) {
                 DoProjectedPoint(&ap);
@@ -236,8 +236,8 @@ void Constraint::DrawOrGetDistance(Vector *labelPos) {
 
         case PT_FACE_DISTANCE:
         case PT_PLANE_DISTANCE: {
-            Vector pt = SS.GetEntity(ptA)->PointGetNum();
-            Entity *enta = SS.GetEntity(entityA);
+            Vector pt = SK.GetEntity(ptA)->PointGetNum();
+            Entity *enta = SK.GetEntity(entityA);
             Vector n, p;
             if(type == PT_PLANE_DISTANCE) {
                 n = enta->Normal()->NormalN();
@@ -258,10 +258,10 @@ void Constraint::DrawOrGetDistance(Vector *labelPos) {
         }
 
         case PT_LINE_DISTANCE: {
-            Vector pt = SS.GetEntity(ptA)->PointGetNum();
-            Entity *line = SS.GetEntity(entityA);
-            Vector lA = SS.GetEntity(line->point[0])->PointGetNum();
-            Vector lB = SS.GetEntity(line->point[1])->PointGetNum();
+            Vector pt = SK.GetEntity(ptA)->PointGetNum();
+            Entity *line = SK.GetEntity(entityA);
+            Vector lA = SK.GetEntity(line->point[0])->PointGetNum();
+            Vector lB = SK.GetEntity(line->point[1])->PointGetNum();
 
             if(workplane.v != Entity::FREE_IN_3D.v) {
                 lA = lA.ProjectInto(workplane);
@@ -282,8 +282,8 @@ void Constraint::DrawOrGetDistance(Vector *labelPos) {
                 Vector lAB = (lA.Minus(lB));
                 double t = (lA.Minus(closest)).DivPivoting(lAB);
 
-                Vector lA = SS.GetEntity(line->point[0])->PointGetNum();
-                Vector lB = SS.GetEntity(line->point[1])->PointGetNum();
+                Vector lA = SK.GetEntity(line->point[0])->PointGetNum();
+                Vector lB = SK.GetEntity(line->point[1])->PointGetNum();
 
                 Vector c2 = (lA.ScaledBy(1-t)).Plus(lB.ScaledBy(t));
                 DoProjectedPoint(&c2);
@@ -292,8 +292,8 @@ void Constraint::DrawOrGetDistance(Vector *labelPos) {
         }
 
         case DIAMETER: {
-            Entity *circle = SS.GetEntity(entityA);
-            Vector center = SS.GetEntity(circle->point[0])->PointGetNum();
+            Entity *circle = SK.GetEntity(entityA);
+            Vector center = SK.GetEntity(circle->point[0])->PointGetNum();
             double r = circle->CircleGetRadiusNum();
             Vector ref = center.Plus(disp.offset);
 
@@ -313,7 +313,7 @@ void Constraint::DrawOrGetDistance(Vector *labelPos) {
         case POINTS_COINCIDENT: {
             if(!dogd.drawing) {
                 for(int i = 0; i < 2; i++) {
-                    Vector p = SS.GetEntity(i == 0 ? ptA : ptB)-> PointGetNum();
+                    Vector p = SK.GetEntity(i == 0 ? ptA : ptB)-> PointGetNum();
                     Point2d pp = SS.GW.ProjectPoint(p);
                     // The point is selected within a radius of 7, from the
                     // same center; so if the point is visible, then this
@@ -328,7 +328,7 @@ void Constraint::DrawOrGetDistance(Vector *labelPos) {
                 Vector r = SS.GW.projRight.ScaledBy((a+1)/SS.GW.scale);
                 Vector d = SS.GW.projUp.ScaledBy((2-a)/SS.GW.scale);
                 for(int i = 0; i < 2; i++) {
-                    Vector p = SS.GetEntity(i == 0 ? ptA : ptB)-> PointGetNum();
+                    Vector p = SK.GetEntity(i == 0 ? ptA : ptB)-> PointGetNum();
                     glxColor3d(0.4, 0, 0.4);
                     glBegin(GL_QUADS);
                         glxVertex3v(p.Plus (r).Plus (d));
@@ -347,14 +347,14 @@ void Constraint::DrawOrGetDistance(Vector *labelPos) {
         case PT_ON_FACE:
         case PT_IN_PLANE: {
             double s = 8/SS.GW.scale;
-            Vector p = SS.GetEntity(ptA)->PointGetNum();
+            Vector p = SK.GetEntity(ptA)->PointGetNum();
             Vector r, d;
             if(type == PT_ON_FACE) {
-                Vector n = SS.GetEntity(entityA)->FaceGetNormalNum();
+                Vector n = SK.GetEntity(entityA)->FaceGetNormalNum();
                 r = n.Normal(0);
                 d = n.Normal(1);
             } else if(type == PT_IN_PLANE) {
-                Entity *n = SS.GetEntity(entityA)->Normal();
+                Entity *n = SK.GetEntity(entityA)->Normal();
                 r = n->NormalU();
                 d = n->NormalV();
             } else {
@@ -372,11 +372,11 @@ void Constraint::DrawOrGetDistance(Vector *labelPos) {
 
         case SAME_ORIENTATION: {
             for(int i = 0; i < 2; i++) {
-                Entity *e = SS.GetEntity(i == 0 ? entityA : entityB);
+                Entity *e = SK.GetEntity(i == 0 ? entityA : entityB);
                 Quaternion q = e->NormalGetNum();
                 Vector n = q.RotationN().WithMagnitude(25/SS.GW.scale);
                 Vector u = q.RotationU().WithMagnitude(6/SS.GW.scale);
-                Vector p = SS.GetEntity(e->point[0])->PointGetNum();
+                Vector p = SK.GetEntity(e->point[0])->PointGetNum();
                 p = p.Plus(n.WithMagnitude(10/SS.GW.scale));
 
                 LineDrawOrGetDistance(p.Plus(u), p.Minus(u).Plus(n));
@@ -387,10 +387,10 @@ void Constraint::DrawOrGetDistance(Vector *labelPos) {
 
         case EQUAL_ANGLE: {
             Vector ref;
-            Entity *a = SS.GetEntity(entityA);
-            Entity *b = SS.GetEntity(entityB);
-            Entity *c = SS.GetEntity(entityC);
-            Entity *d = SS.GetEntity(entityD);
+            Entity *a = SK.GetEntity(entityA);
+            Entity *b = SK.GetEntity(entityB);
+            Entity *c = SK.GetEntity(entityC);
+            Entity *d = SK.GetEntity(entityD);
 
             Vector a0 = a->VectorGetRefPoint();
             Vector b0 = b->VectorGetRefPoint();
@@ -412,8 +412,8 @@ void Constraint::DrawOrGetDistance(Vector *labelPos) {
         }
 
         case ANGLE: {
-            Entity *a = SS.GetEntity(entityA);
-            Entity *b = SS.GetEntity(entityB);
+            Entity *a = SK.GetEntity(entityA);
+            Entity *b = SK.GetEntity(entityB);
             
             Vector a0 = a->VectorGetRefPoint();
             Vector b0 = b->VectorGetRefPoint();
@@ -434,13 +434,13 @@ void Constraint::DrawOrGetDistance(Vector *labelPos) {
                 rn = gn;
                 ru = gu;
             } else {
-                Entity *normal = SS.GetEntity(workplane)->Normal();
+                Entity *normal = SK.GetEntity(workplane)->Normal();
                 rn = normal->NormalN();
                 ru = normal->NormalV(); // ru meaning r_up, not u/v
             }
 
             for(int i = 0; i < 2; i++) {
-                Entity *e = SS.GetEntity(i == 0 ? entityA : entityB);
+                Entity *e = SK.GetEntity(i == 0 ? entityA : entityB);
 
                 if(i == 0) {
                     // Calculate orientation of perpendicular sign only
@@ -469,11 +469,11 @@ void Constraint::DrawOrGetDistance(Vector *labelPos) {
             Vector textAt, u, v;
 
             if(type == ARC_LINE_TANGENT) {
-                Entity *arc = SS.GetEntity(entityA);
-                Entity *norm = SS.GetEntity(arc->normal);
-                Vector c = SS.GetEntity(arc->point[0])->PointGetNum();
+                Entity *arc = SK.GetEntity(entityA);
+                Entity *norm = SK.GetEntity(arc->normal);
+                Vector c = SK.GetEntity(arc->point[0])->PointGetNum();
                 Vector p = 
-                    SS.GetEntity(arc->point[other ? 2 : 1])->PointGetNum();
+                    SK.GetEntity(arc->point[other ? 2 : 1])->PointGetNum();
                 Vector r = p.Minus(c);
                 textAt = p.Plus(r.WithMagnitude(14/SS.GW.scale));
                 u = norm->NormalU();
@@ -485,16 +485,16 @@ void Constraint::DrawOrGetDistance(Vector *labelPos) {
                     v = gu;
                     n = gn;
                 } else {
-                    Entity *wn = SS.GetEntity(workplane)->Normal();
+                    Entity *wn = SK.GetEntity(workplane)->Normal();
                     u = wn->NormalU();
                     v = wn->NormalV();
                     n = wn->NormalN();
                 }
 
-                Entity *cubic = SS.GetEntity(entityA);
+                Entity *cubic = SK.GetEntity(entityA);
                 Vector p =
-                    SS.GetEntity(cubic->point[other ? 3 : 0])->PointGetNum();
-                Vector dir = SS.GetEntity(entityB)->VectorGetNum();
+                    SK.GetEntity(cubic->point[other ? 3 : 0])->PointGetNum();
+                Vector dir = SK.GetEntity(entityB)->VectorGetNum();
                 Vector out = n.Cross(dir);
                 textAt = p.Plus(out.WithMagnitude(14/SS.GW.scale));
             }
@@ -515,7 +515,7 @@ void Constraint::DrawOrGetDistance(Vector *labelPos) {
 
         case PARALLEL: {
             for(int i = 0; i < 2; i++) {
-                Entity *e = SS.GetEntity(i == 0 ? entityA : entityB);
+                Entity *e = SK.GetEntity(i == 0 ? entityA : entityB);
                 Vector n = e->VectorGetNum();
                 n = n.WithMagnitude(25/SS.GW.scale);
                 Vector u = (gn.Cross(n)).WithMagnitude(4/SS.GW.scale);
@@ -535,10 +535,10 @@ void Constraint::DrawOrGetDistance(Vector *labelPos) {
         }
 
         case EQUAL_LINE_ARC_LEN: {
-            Entity *line = SS.GetEntity(entityA);
+            Entity *line = SK.GetEntity(entityA);
             DoEqualLenTicks(
-                SS.GetEntity(line->point[0])->PointGetNum(),
-                SS.GetEntity(line->point[1])->PointGetNum(),
+                SK.GetEntity(line->point[0])->PointGetNum(),
+                SK.GetEntity(line->point[1])->PointGetNum(),
                 gn);
 
             DoEqualRadiusTicks(entityB);
@@ -549,9 +549,9 @@ void Constraint::DrawOrGetDistance(Vector *labelPos) {
         case EQUAL_LENGTH_LINES: {
             Vector a, b;
             for(int i = 0; i < 2; i++) {
-                Entity *e = SS.GetEntity(i == 0 ? entityA : entityB);
-                a = SS.GetEntity(e->point[0])->PointGetNum();
-                b = SS.GetEntity(e->point[1])->PointGetNum();
+                Entity *e = SK.GetEntity(i == 0 ? entityA : entityB);
+                a = SK.GetEntity(e->point[0])->PointGetNum();
+                b = SK.GetEntity(e->point[1])->PointGetNum();
 
                 if(workplane.v != Entity::FREE_IN_3D.v) {
                     DoProjectedPoint(&a);
@@ -568,19 +568,19 @@ void Constraint::DrawOrGetDistance(Vector *labelPos) {
         }
 
         case EQ_LEN_PT_LINE_D: {
-            Entity *forLen = SS.GetEntity(entityA);
-            Vector a = SS.GetEntity(forLen->point[0])->PointGetNum(),
-                   b = SS.GetEntity(forLen->point[1])->PointGetNum();
+            Entity *forLen = SK.GetEntity(entityA);
+            Vector a = SK.GetEntity(forLen->point[0])->PointGetNum(),
+                   b = SK.GetEntity(forLen->point[1])->PointGetNum();
             if(workplane.v != Entity::FREE_IN_3D.v) {
                 DoProjectedPoint(&a);
                 DoProjectedPoint(&b);
             }
             DoEqualLenTicks(a, b, gn);
 
-            Entity *ln = SS.GetEntity(entityB);
-            Vector la = SS.GetEntity(ln->point[0])->PointGetNum(),
-                   lb = SS.GetEntity(ln->point[1])->PointGetNum();
-            Vector pt = SS.GetEntity(ptA)->PointGetNum();
+            Entity *ln = SK.GetEntity(entityB);
+            Vector la = SK.GetEntity(ln->point[0])->PointGetNum(),
+                   lb = SK.GetEntity(ln->point[1])->PointGetNum();
+            Vector pt = SK.GetEntity(ptA)->PointGetNum();
             if(workplane.v != Entity::FREE_IN_3D.v) {
                 DoProjectedPoint(&pt);
                 la = la.ProjectInto(workplane);
@@ -595,10 +595,10 @@ void Constraint::DrawOrGetDistance(Vector *labelPos) {
 
         case EQ_PT_LN_DISTANCES: {
             for(int i = 0; i < 2; i++) {
-                Entity *ln = SS.GetEntity(i == 0 ? entityA : entityB);
-                Vector la = SS.GetEntity(ln->point[0])->PointGetNum(),
-                       lb = SS.GetEntity(ln->point[1])->PointGetNum();
-                Entity *pte = SS.GetEntity(i == 0 ? ptA : ptB);
+                Entity *ln = SK.GetEntity(i == 0 ? entityA : entityB);
+                Vector la = SK.GetEntity(ln->point[0])->PointGetNum(),
+                       lb = SK.GetEntity(ln->point[1])->PointGetNum();
+                Entity *pte = SK.GetEntity(i == 0 ? ptA : ptB);
                 Vector pt = pte->PointGetNum();
 
                 if(workplane.v != Entity::FREE_IN_3D.v) {
@@ -618,25 +618,25 @@ void Constraint::DrawOrGetDistance(Vector *labelPos) {
         {
         Vector n; 
         case SYMMETRIC:
-            n = SS.GetEntity(entityA)->Normal()->NormalN(); goto s;
+            n = SK.GetEntity(entityA)->Normal()->NormalN(); goto s;
         case SYMMETRIC_HORIZ:
-            n = SS.GetEntity(workplane)->Normal()->NormalU(); goto s;
+            n = SK.GetEntity(workplane)->Normal()->NormalU(); goto s;
         case SYMMETRIC_VERT:
-            n = SS.GetEntity(workplane)->Normal()->NormalV(); goto s;
+            n = SK.GetEntity(workplane)->Normal()->NormalV(); goto s;
         case SYMMETRIC_LINE: {
-            Entity *ln = SS.GetEntity(entityA);
-            Vector la = SS.GetEntity(ln->point[0])->PointGetNum(),
-                   lb = SS.GetEntity(ln->point[1])->PointGetNum();
+            Entity *ln = SK.GetEntity(entityA);
+            Vector la = SK.GetEntity(ln->point[0])->PointGetNum(),
+                   lb = SK.GetEntity(ln->point[1])->PointGetNum();
             la = la.ProjectInto(workplane);
             lb = lb.ProjectInto(workplane);
             n = lb.Minus(la);
-            Vector nw = SS.GetEntity(workplane)->Normal()->NormalN();
+            Vector nw = SK.GetEntity(workplane)->Normal()->NormalN();
             n = n.RotatedAbout(nw, PI/2);
             goto s;
         }
 s:
-            Vector a = SS.GetEntity(ptA)->PointGetNum();
-            Vector b = SS.GetEntity(ptB)->PointGetNum();
+            Vector a = SK.GetEntity(ptA)->PointGetNum();
+            Vector b = SK.GetEntity(ptB)->PointGetNum();
 
             for(int i = 0; i < 2; i++) {
                 Vector tail = (i == 0) ? a : b;
@@ -666,14 +666,14 @@ s:
                 if(workplane.v == Entity::FREE_IN_3D.v) {
                     r = gr; u = gu; n = gn;
                 } else {
-                    r = SS.GetEntity(workplane)->Normal()->NormalU();
-                    u = SS.GetEntity(workplane)->Normal()->NormalV();
+                    r = SK.GetEntity(workplane)->Normal()->NormalU();
+                    u = SK.GetEntity(workplane)->Normal()->NormalV();
                     n = r.Cross(u);
                 }
                 // For "at midpoint", this branch is always taken.
-                Entity *e = SS.GetEntity(entityA);
-                Vector a = SS.GetEntity(e->point[0])->PointGetNum();
-                Vector b = SS.GetEntity(e->point[1])->PointGetNum();
+                Entity *e = SK.GetEntity(entityA);
+                Vector a = SK.GetEntity(e->point[0])->PointGetNum();
+                Vector b = SK.GetEntity(e->point[1])->PointGetNum();
                 Vector m = (a.ScaledBy(0.5)).Plus(b.ScaledBy(0.5));
                 Vector offset = (a.Minus(b)).Cross(n);
                 offset = offset.WithMagnitude(13/SS.GW.scale);
@@ -696,10 +696,10 @@ s:
                     dogd.dmin = min(dogd.dmin, ref.DistanceTo(dogd.mp)-10);
                 }
             } else {
-                Vector a = SS.GetEntity(ptA)->PointGetNum();
-                Vector b = SS.GetEntity(ptB)->PointGetNum();
+                Vector a = SK.GetEntity(ptA)->PointGetNum();
+                Vector b = SK.GetEntity(ptB)->PointGetNum();
 
-                Entity *w = SS.GetEntity(workplane);
+                Entity *w = SK.GetEntity(workplane);
                 Vector cu = w->Normal()->NormalU();
                 Vector cv = w->Normal()->NormalV();
                 Vector cn = w->Normal()->NormalN();
diff --git a/drawentity.cpp b/drawentity.cpp
index a6d38f5d..697196af 100644
--- a/drawentity.cpp
+++ b/drawentity.cpp
@@ -2,10 +2,10 @@
 
 char *Entity::DescriptionString(void) {
     if(h.isFromRequest()) {
-        Request *r = SS.GetRequest(h.request());
+        Request *r = SK.GetRequest(h.request());
         return r->DescriptionString();
     } else {
-        Group *g = SS.GetGroup(h.group());
+        Group *g = SK.GetGroup(h.group());
         return g->DescriptionString();
     }
 }
@@ -43,10 +43,10 @@ void Entity::DrawAll(void) {
         glxColor3d(0, 0.8, 0);
         glxDepthRangeOffset(6);
         glBegin(GL_QUADS);
-        for(i = 0; i < SS.entity.n; i++) {
-            Entity *e = &(SS.entity.elem[i]);
+        for(i = 0; i < SK.entity.n; i++) {
+            Entity *e = &(SK.entity.elem[i]);
             if(!e->IsPoint()) continue;
-            if(!(SS.GetGroup(e->group)->visible)) continue;
+            if(!(SK.GetGroup(e->group)->visible)) continue;
             if(SS.GroupsInOrder(SS.GW.activeGroup, e->group)) continue;
             if(e->forceHidden) continue;
 
@@ -54,14 +54,14 @@ void Entity::DrawAll(void) {
 
             bool free = false;
             if(e->type == POINT_IN_3D) {
-                Param *px = SS.GetParam(e->param[0]),
-                      *py = SS.GetParam(e->param[1]),
-                      *pz = SS.GetParam(e->param[2]);
+                Param *px = SK.GetParam(e->param[0]),
+                      *py = SK.GetParam(e->param[1]),
+                      *pz = SK.GetParam(e->param[2]);
 
                 free = (px->free) || (py->free) || (pz->free);
             } else if(e->type == POINT_IN_2D) {
-                Param *pu = SS.GetParam(e->param[0]),
-                      *pv = SS.GetParam(e->param[1]);
+                Param *pu = SK.GetParam(e->param[0]),
+                      *pv = SK.GetParam(e->param[1]);
 
                 free = (pu->free) || (pv->free);
             }
@@ -86,8 +86,8 @@ void Entity::DrawAll(void) {
     }
 
     glLineWidth(1.5);
-    for(i = 0; i < SS.entity.n; i++) {
-        Entity *e = &(SS.entity.elem[i]);
+    for(i = 0; i < SK.entity.n; i++) {
+        Entity *e = &(SK.entity.elem[i]);
         if(e->IsPoint())
         {
             continue; // already handled
@@ -145,7 +145,7 @@ Vector Entity::GetReferencePos(void) {
 }
 
 bool Entity::IsVisible(void) {
-    Group *g = SS.GetGroup(group);
+    Group *g = SK.GetGroup(group);
 
     if(g->h.v == Group::HGROUP_REFERENCES.v && IsNormal()) {
         // The reference normals are always shown
@@ -178,17 +178,17 @@ void Entity::GenerateBezierCurves(SBezierList  *sbl) {
 
     switch(type) {
         case LINE_SEGMENT: {
-            Vector a = SS.GetEntity(point[0])->PointGetNum();
-            Vector b = SS.GetEntity(point[1])->PointGetNum();
+            Vector a = SK.GetEntity(point[0])->PointGetNum();
+            Vector b = SK.GetEntity(point[1])->PointGetNum();
             sb = SBezier::From(a, b);
             sbl->l.Add(&sb);
             break;
         }
         case CUBIC: {
-            Vector p0 = SS.GetEntity(point[0])->PointGetNum();
-            Vector p1 = SS.GetEntity(point[1])->PointGetNum();
-            Vector p2 = SS.GetEntity(point[2])->PointGetNum();
-            Vector p3 = SS.GetEntity(point[3])->PointGetNum();
+            Vector p0 = SK.GetEntity(point[0])->PointGetNum();
+            Vector p1 = SK.GetEntity(point[1])->PointGetNum();
+            Vector p2 = SK.GetEntity(point[2])->PointGetNum();
+            Vector p3 = SK.GetEntity(point[3])->PointGetNum();
             sb = SBezier::From(p0, p1, p2, p3);
             sbl->l.Add(&sb);
             break;
@@ -196,8 +196,8 @@ void Entity::GenerateBezierCurves(SBezierList  *sbl) {
 
         case CIRCLE:
         case ARC_OF_CIRCLE: {
-            Vector center = SS.GetEntity(point[0])->PointGetNum();
-            Quaternion q = SS.GetEntity(normal)->NormalGetNum();
+            Vector center = SK.GetEntity(point[0])->PointGetNum();
+            Quaternion q = SK.GetEntity(normal)->NormalGetNum();
             Vector u = q.RotationU(), v = q.RotationV();
             double r = CircleGetRadiusNum();
             double thetaa, thetab, dtheta;
@@ -257,8 +257,8 @@ void Entity::GenerateBezierCurves(SBezierList  *sbl) {
         }
             
         case TTF_TEXT: {
-            Vector topLeft = SS.GetEntity(point[0])->PointGetNum();
-            Vector botLeft = SS.GetEntity(point[1])->PointGetNum();
+            Vector topLeft = SK.GetEntity(point[0])->PointGetNum();
+            Vector botLeft = SK.GetEntity(point[1])->PointGetNum();
             Vector n = Normal()->NormalN();
             Vector v = topLeft.Minus(botLeft);
             Vector u = (v.Cross(n)).WithMagnitude(v.Magnitude());
@@ -276,7 +276,7 @@ void Entity::GenerateBezierCurves(SBezierList  *sbl) {
 void Entity::DrawOrGetDistance(void) {
     if(!IsVisible()) return;
 
-    Group *g = SS.GetGroup(group);
+    Group *g = SK.GetGroup(group);
 
     if(group.v != SS.GW.activeGroup.v) {
         glxColor3d(0.5, 0.3, 0.0);
@@ -340,7 +340,7 @@ void Entity::DrawOrGetDistance(void) {
                 Quaternion q = NormalGetNum();
                 Vector tail;
                 if(i == 0) {
-                    tail = SS.GetEntity(point[0])->PointGetNum();
+                    tail = SK.GetEntity(point[0])->PointGetNum();
                     glLineWidth(1);
                 } else {
                     // Draw an extra copy of the x, y, and z axes, that's
@@ -376,7 +376,7 @@ void Entity::DrawOrGetDistance(void) {
 
         case WORKPLANE: {
             Vector p;
-            p = SS.GetEntity(point[0])->PointGetNum();
+            p = SK.GetEntity(point[0])->PointGetNum();
 
             Vector u = Normal()->NormalU();
             Vector v = Normal()->NormalV();
diff --git a/entity.cpp b/entity.cpp
index 9301eb8d..51055414 100644
--- a/entity.cpp
+++ b/entity.cpp
@@ -21,8 +21,8 @@ bool EntityBase::HasVector(void) {
 ExprVector EntityBase::VectorGetExprs(void) {
     switch(type) {
         case LINE_SEGMENT:
-            return (SS.GetEntity(point[0])->PointGetExprs()).Minus(
-                    SS.GetEntity(point[1])->PointGetExprs());
+            return (SK.GetEntity(point[0])->PointGetExprs()).Minus(
+                    SK.GetEntity(point[1])->PointGetExprs());
 
         case NORMAL_IN_3D:
         case NORMAL_IN_2D:
@@ -38,8 +38,8 @@ ExprVector EntityBase::VectorGetExprs(void) {
 Vector EntityBase::VectorGetNum(void) {
     switch(type) {
         case LINE_SEGMENT:
-            return (SS.GetEntity(point[0])->PointGetNum()).Minus(
-                    SS.GetEntity(point[1])->PointGetNum());
+            return (SK.GetEntity(point[0])->PointGetNum()).Minus(
+                    SK.GetEntity(point[1])->PointGetNum());
 
         case NORMAL_IN_3D:
         case NORMAL_IN_2D:
@@ -55,15 +55,15 @@ Vector EntityBase::VectorGetNum(void) {
 Vector EntityBase::VectorGetRefPoint(void) {
     switch(type) {
         case LINE_SEGMENT:
-            return ((SS.GetEntity(point[0])->PointGetNum()).Plus(
-                     SS.GetEntity(point[1])->PointGetNum())).ScaledBy(0.5);
+            return ((SK.GetEntity(point[0])->PointGetNum()).Plus(
+                     SK.GetEntity(point[1])->PointGetNum())).ScaledBy(0.5);
 
         case NORMAL_IN_3D:
         case NORMAL_IN_2D:
         case NORMAL_N_COPY:
         case NORMAL_N_ROT:
         case NORMAL_N_ROT_AA:
-            return SS.GetEntity(point[0])->PointGetNum();
+            return SK.GetEntity(point[0])->PointGetNum();
 
         default: oops();
     }
@@ -75,7 +75,7 @@ bool EntityBase::IsCircle(void) {
 
 Expr *EntityBase::CircleGetRadiusExpr(void) {
     if(type == CIRCLE) {
-        return SS.GetEntity(distance)->DistanceGetExpr();
+        return SK.GetEntity(distance)->DistanceGetExpr();
     } else if(type == ARC_OF_CIRCLE) {
         return Constraint::Distance(workplane, point[0], point[1]);
     } else oops();
@@ -83,10 +83,10 @@ Expr *EntityBase::CircleGetRadiusExpr(void) {
 
 double EntityBase::CircleGetRadiusNum(void) {
     if(type == CIRCLE) {
-        return SS.GetEntity(distance)->DistanceGetNum();
+        return SK.GetEntity(distance)->DistanceGetNum();
     } else if(type == ARC_OF_CIRCLE) {
-        Vector c  = SS.GetEntity(point[0])->PointGetNum();
-        Vector pa = SS.GetEntity(point[1])->PointGetNum();
+        Vector c  = SK.GetEntity(point[0])->PointGetNum();
+        Vector pa = SK.GetEntity(point[1])->PointGetNum();
         return (pa.Minus(c)).Magnitude();
     } else oops();
 }
@@ -97,9 +97,9 @@ void EntityBase::ArcGetAngles(double *thetaa, double *thetab, double *dtheta) {
     Quaternion q = Normal()->NormalGetNum();
     Vector u = q.RotationU(), v = q.RotationV();
 
-    Vector c  = SS.GetEntity(point[0])->PointGetNum();
-    Vector pa = SS.GetEntity(point[1])->PointGetNum();
-    Vector pb = SS.GetEntity(point[2])->PointGetNum();
+    Vector c  = SK.GetEntity(point[0])->PointGetNum();
+    Vector pa = SK.GetEntity(point[1])->PointGetNum();
+    Vector pb = SK.GetEntity(point[2])->PointGetNum();
 
     Point2d c2  = c.Project2d(u, v);
     Point2d pa2 = (pa.Project2d(u, v)).Minus(c2);
@@ -119,18 +119,18 @@ bool EntityBase::IsWorkplane(void) {
 }
 
 ExprVector EntityBase::WorkplaneGetOffsetExprs(void) {
-    return SS.GetEntity(point[0])->PointGetExprs();
+    return SK.GetEntity(point[0])->PointGetExprs();
 }
 
 Vector EntityBase::WorkplaneGetOffset(void) {
-    return SS.GetEntity(point[0])->PointGetNum();
+    return SK.GetEntity(point[0])->PointGetNum();
 }
 
 void EntityBase::WorkplaneGetPlaneExprs(ExprVector *n, Expr **dn) {
     if(type == WORKPLANE) {
         *n = Normal()->NormalExprsN();
 
-        ExprVector p0 = SS.GetEntity(point[0])->PointGetExprs();
+        ExprVector p0 = SK.GetEntity(point[0])->PointGetExprs();
         // The plane is n dot (p - p0) = 0, or
         //              n dot p - n dot p0 = 0
         // so dn = n dot p0
@@ -142,7 +142,7 @@ void EntityBase::WorkplaneGetPlaneExprs(ExprVector *n, Expr **dn) {
 
 double EntityBase::DistanceGetNum(void) {
     if(type == DISTANCE) {
-        return SS.GetParam(param[0])->val;
+        return SK.GetParam(param[0])->val;
     } else if(type == DISTANCE_N_COPY) {
         return numDistance;
     } else oops();
@@ -156,14 +156,14 @@ Expr *EntityBase::DistanceGetExpr(void) {
 }
 void EntityBase::DistanceForceTo(double v) {
     if(type == DISTANCE) {
-        (SS.GetParam(param[0]))->val = v;
+        (SK.GetParam(param[0]))->val = v;
     } else if(type == DISTANCE_N_COPY) {
         // do nothing, it's locked
     } else oops();
 }
 
 Entity *EntityBase::Normal(void) {
-    return SS.GetEntity(normal);
+    return SK.GetEntity(normal);
 }
 
 bool EntityBase::IsPoint(void) {
@@ -202,8 +202,8 @@ Quaternion EntityBase::NormalGetNum(void) {
             break;
 
         case NORMAL_IN_2D: {
-            Entity *wrkpl = SS.GetEntity(workplane);
-            Entity *norm = SS.GetEntity(wrkpl->normal);
+            Entity *wrkpl = SK.GetEntity(workplane);
+            Entity *norm = SK.GetEntity(wrkpl->normal);
             q = norm->NormalGetNum();
             break;
         }
@@ -230,10 +230,10 @@ Quaternion EntityBase::NormalGetNum(void) {
 void EntityBase::NormalForceTo(Quaternion q) {
     switch(type) {
         case NORMAL_IN_3D:
-            SS.GetParam(param[0])->val = q.w;
-            SS.GetParam(param[1])->val = q.vx;
-            SS.GetParam(param[2])->val = q.vy;
-            SS.GetParam(param[3])->val = q.vz;
+            SK.GetParam(param[0])->val = q.w;
+            SK.GetParam(param[1])->val = q.vx;
+            SK.GetParam(param[2])->val = q.vy;
+            SK.GetParam(param[3])->val = q.vz;
             break;
 
         case NORMAL_IN_2D:
@@ -243,10 +243,10 @@ void EntityBase::NormalForceTo(Quaternion q) {
         case NORMAL_N_ROT: {
             Quaternion qp = q.Times(numNormal.Inverse());
             
-            SS.GetParam(param[0])->val = qp.w;
-            SS.GetParam(param[1])->val = qp.vx;
-            SS.GetParam(param[2])->val = qp.vy;
-            SS.GetParam(param[3])->val = qp.vz;
+            SK.GetParam(param[0])->val = qp.w;
+            SK.GetParam(param[1])->val = qp.vx;
+            SK.GetParam(param[2])->val = qp.vy;
+            SK.GetParam(param[3])->val = qp.vz;
             break;
         }
 
@@ -286,8 +286,8 @@ ExprQuaternion EntityBase::NormalGetExprs(void) {
             break;
 
         case NORMAL_IN_2D: {
-            Entity *wrkpl = SS.GetEntity(workplane);
-            Entity *norm = SS.GetEntity(wrkpl->normal);
+            Entity *wrkpl = SK.GetEntity(workplane);
+            Entity *norm = SK.GetEntity(wrkpl->normal);
             q = norm->NormalGetExprs();
             break;
         }
@@ -322,25 +322,25 @@ bool EntityBase::PointIsFromReferences(void) {
 void EntityBase::PointForceTo(Vector p) {
     switch(type) {
         case POINT_IN_3D:
-            SS.GetParam(param[0])->val = p.x;
-            SS.GetParam(param[1])->val = p.y;
-            SS.GetParam(param[2])->val = p.z;
+            SK.GetParam(param[0])->val = p.x;
+            SK.GetParam(param[1])->val = p.y;
+            SK.GetParam(param[2])->val = p.z;
             break;
 
         case POINT_IN_2D: {
-            Entity *c = SS.GetEntity(workplane);
+            Entity *c = SK.GetEntity(workplane);
             p = p.Minus(c->WorkplaneGetOffset());
-            SS.GetParam(param[0])->val = p.Dot(c->Normal()->NormalU());
-            SS.GetParam(param[1])->val = p.Dot(c->Normal()->NormalV());
+            SK.GetParam(param[0])->val = p.Dot(c->Normal()->NormalU());
+            SK.GetParam(param[1])->val = p.Dot(c->Normal()->NormalV());
             break;
         }
 
         case POINT_N_TRANS: {
             if(timesApplied == 0) break;
             Vector trans = (p.Minus(numPoint)).ScaledBy(1.0/timesApplied);
-            SS.GetParam(param[0])->val = trans.x;
-            SS.GetParam(param[1])->val = trans.y;
-            SS.GetParam(param[2])->val = trans.z;
+            SK.GetParam(param[0])->val = trans.x;
+            SK.GetParam(param[1])->val = trans.y;
+            SK.GetParam(param[2])->val = trans.z;
             break;
         }
 
@@ -349,9 +349,9 @@ void EntityBase::PointForceTo(Vector p) {
             // remember that we're working with respect to the rotated
             // point.
             Vector trans = p.Minus(PointGetQuaternion().Rotate(numPoint));
-            SS.GetParam(param[0])->val = trans.x;
-            SS.GetParam(param[1])->val = trans.y;
-            SS.GetParam(param[2])->val = trans.z;
+            SK.GetParam(param[0])->val = trans.x;
+            SK.GetParam(param[1])->val = trans.y;
+            SK.GetParam(param[2])->val = trans.z;
             break;
         }
 
@@ -364,13 +364,13 @@ void EntityBase::PointForceTo(Vector p) {
             double thetap = atan2(v.Dot(po), u.Dot(po));
             double thetan = atan2(v.Dot(numo), u.Dot(numo));
             double thetaf = (thetap - thetan);
-            double thetai = (SS.GetParam(param[3])->val)*timesApplied*2;
+            double thetai = (SK.GetParam(param[3])->val)*timesApplied*2;
             double dtheta = thetaf - thetai;
             // Take the smallest possible change in the actual step angle,
             // in order to avoid jumps when you cross from +pi to -pi
             while(dtheta < -PI) dtheta += 2*PI;
             while(dtheta > PI) dtheta -= 2*PI;
-            SS.GetParam(param[3])->val = (thetai + dtheta)/(timesApplied*2);
+            SK.GetParam(param[3])->val = (thetai + dtheta)/(timesApplied*2);
             break;
         }
 
@@ -390,11 +390,11 @@ Vector EntityBase::PointGetNum(void) {
             break;
 
         case POINT_IN_2D: {
-            Entity *c = SS.GetEntity(workplane);
+            Entity *c = SK.GetEntity(workplane);
             Vector u = c->Normal()->NormalU();
             Vector v = c->Normal()->NormalV();
-            p =        u.ScaledBy(SS.GetParam(param[0])->val);
-            p = p.Plus(v.ScaledBy(SS.GetParam(param[1])->val));
+            p =        u.ScaledBy(SK.GetParam(param[0])->val);
+            p = p.Plus(v.ScaledBy(SK.GetParam(param[1])->val));
             p = p.Plus(c->WorkplaneGetOffset());
             break;
         }
@@ -439,7 +439,7 @@ ExprVector EntityBase::PointGetExprs(void) {
             break;
 
         case POINT_IN_2D: {
-            Entity *c = SS.GetEntity(workplane);
+            Entity *c = SK.GetEntity(workplane);
             ExprVector u = c->Normal()->NormalExprsU();
             ExprVector v = c->Normal()->NormalExprsV();
             r = c->WorkplaneGetOffsetExprs();
@@ -488,7 +488,7 @@ void EntityBase::PointGetExprsInWorkplane(hEntity wrkpl, Expr **u, Expr **v) {
         *v = Expr::From(param[1]);
     } else {
         // Get the offset and basis vectors for this weird exotic csys.
-        Entity *w = SS.GetEntity(wrkpl);
+        Entity *w = SK.GetEntity(wrkpl);
         ExprVector wp = w->WorkplaneGetOffsetExprs();
         ExprVector wu = w->Normal()->NormalExprsU();
         ExprVector wv = w->Normal()->NormalExprsV();
@@ -505,20 +505,20 @@ void EntityBase::PointGetExprsInWorkplane(hEntity wrkpl, Expr **u, Expr **v) {
 void EntityBase::PointForceQuaternionTo(Quaternion q) {
     if(type != POINT_N_ROT_TRANS) oops();
 
-    SS.GetParam(param[3])->val = q.w;
-    SS.GetParam(param[4])->val = q.vx;
-    SS.GetParam(param[5])->val = q.vy;
-    SS.GetParam(param[6])->val = q.vz;
+    SK.GetParam(param[3])->val = q.w;
+    SK.GetParam(param[4])->val = q.vx;
+    SK.GetParam(param[5])->val = q.vy;
+    SK.GetParam(param[6])->val = q.vz;
 }
 
 Quaternion EntityBase::GetAxisAngleQuaternion(int param0) {
     Quaternion q;
-    double theta = timesApplied*SS.GetParam(param[param0+0])->val;
+    double theta = timesApplied*SK.GetParam(param[param0+0])->val;
     double s = sin(theta), c = cos(theta);
     q.w = c;
-    q.vx = s*SS.GetParam(param[param0+1])->val;
-    q.vy = s*SS.GetParam(param[param0+2])->val;
-    q.vz = s*SS.GetParam(param[param0+3])->val;
+    q.vx = s*SK.GetParam(param[param0+1])->val;
+    q.vy = s*SK.GetParam(param[param0+2])->val;
+    q.vz = s*SK.GetParam(param[param0+3])->val;
     return q;
 }
 
@@ -615,7 +615,7 @@ Vector EntityBase::FaceGetNormalNum(void) {
 ExprVector EntityBase::FaceGetPointExprs(void) {
     ExprVector r;
     if(type == FACE_NORMAL_PT) {
-        r = SS.GetEntity(point[0])->PointGetExprs();
+        r = SK.GetEntity(point[0])->PointGetExprs();
     } else if(type == FACE_XPROD) {
         r = ExprVector::From(numPoint);
     } else if(type == FACE_N_ROT_TRANS) {
@@ -644,7 +644,7 @@ ExprVector EntityBase::FaceGetPointExprs(void) {
 Vector EntityBase::FaceGetPointNum(void) {
     Vector r;
     if(type == FACE_NORMAL_PT) {
-        r = SS.GetEntity(point[0])->PointGetNum();
+        r = SK.GetEntity(point[0])->PointGetNum();
     } else if(type == FACE_XPROD) {
         r = numPoint;
     } else if(type == FACE_N_ROT_TRANS) {
@@ -684,7 +684,7 @@ void EntityBase::GenerateEquations(IdList<Equation,hEquation> *l) {
             // If this is a copied entity, with its point already fixed
             // with respect to each other, then we don't want to generate
             // the distance constraint!
-            if(SS.GetEntity(point[0])->type == POINT_IN_2D) {
+            if(SK.GetEntity(point[0])->type == POINT_IN_2D) {
                 Expr *ra = Constraint::Distance(workplane, point[0], point[1]);
                 Expr *rb = Constraint::Distance(workplane, point[0], point[2]);
                 AddEq(l, ra->Minus(rb), 0);
diff --git a/export.cpp b/export.cpp
index bddaae31..a9603791 100644
--- a/export.cpp
+++ b/export.cpp
@@ -5,7 +5,7 @@ void SolveSpace::ExportSectionTo(char *filename) {
     Vector gn = (SS.GW.projRight).Cross(SS.GW.projUp);
     gn = gn.WithMagnitude(1);
 
-    Group *g = SS.GetGroup(SS.GW.activeGroup);
+    Group *g = SK.GetGroup(SS.GW.activeGroup);
     if(g->runningMesh.l.n == 0) {
         Error("No solid model present; draw one with extrudes and revolves, "
               "or use Export 2d View to export bare lines and curves.");
@@ -20,21 +20,21 @@ void SolveSpace::ExportSectionTo(char *filename) {
     SS.GW.GroupSelection();
 #define gs (SS.GW.gs)
     if((gs.n == 0 && g->activeWorkplane.v != Entity::FREE_IN_3D.v)) {
-        Entity *wrkpl = SS.GetEntity(g->activeWorkplane);
+        Entity *wrkpl = SK.GetEntity(g->activeWorkplane);
         origin = wrkpl->WorkplaneGetOffset();
         n = wrkpl->Normal()->NormalN();
         u = wrkpl->Normal()->NormalU();
         v = wrkpl->Normal()->NormalV();
     } else if(gs.n == 1 && gs.faces == 1) {
-        Entity *face = SS.GetEntity(gs.entity[0]);
+        Entity *face = SK.GetEntity(gs.entity[0]);
         origin = face->FaceGetPointNum();
         n = face->FaceGetNormalNum();
         if(n.Dot(gn) < 0) n = n.ScaledBy(-1);
         u = n.Normal(0);
         v = n.Normal(1);
     } else if(gs.n == 3 && gs.vectors == 2 && gs.points == 1) {
-        Vector ut = SS.GetEntity(gs.entity[0])->VectorGetNum(),
-               vt = SS.GetEntity(gs.entity[1])->VectorGetNum();
+        Vector ut = SK.GetEntity(gs.entity[0])->VectorGetNum(),
+               vt = SK.GetEntity(gs.entity[1])->VectorGetNum();
         ut = ut.WithMagnitude(1);
         vt = vt.WithMagnitude(1);
 
@@ -44,7 +44,7 @@ void SolveSpace::ExportSectionTo(char *filename) {
         if(SS.GW.projRight.Dot(ut) < 0) ut = ut.ScaledBy(-1);
         if(SS.GW.projUp.   Dot(vt) < 0) vt = vt.ScaledBy(-1);
 
-        origin = SS.GetEntity(gs.point[0])->PointGetNum();
+        origin = SK.GetEntity(gs.point[0])->PointGetNum();
         n = ut.Cross(vt);
         u = ut.WithMagnitude(1);
         v = (n.Cross(u)).WithMagnitude(1);
@@ -95,14 +95,14 @@ void SolveSpace::ExportViewTo(char *filename) {
 
     SMesh *sm = NULL;
     if(SS.GW.showShaded) {
-        sm = &((SS.GetGroup(SS.GW.activeGroup))->runningMesh);
+        sm = &((SK.GetGroup(SS.GW.activeGroup))->runningMesh);
     }
     if(sm->l.n == 0) {
         sm = NULL;
     }
 
-    for(i = 0; i < SS.entity.n; i++) {
-        Entity *e = &(SS.entity.elem[i]);
+    for(i = 0; i < SK.entity.n; i++) {
+        Entity *e = &(SK.entity.elem[i]);
         if(!e->IsVisible()) continue;
         if(e->construction) continue;
 
@@ -119,7 +119,7 @@ void SolveSpace::ExportViewTo(char *filename) {
     }
 
     if(SS.GW.showEdges) {
-        SEdgeList *selr = &((SS.GetGroup(SS.GW.activeGroup))->runningEdges);
+        SEdgeList *selr = &((SK.GetGroup(SS.GW.activeGroup))->runningEdges);
         SEdge *se;
         for(se = selr->l.First(); se; se = selr->l.NextAfter(se)) {
             edges.AddEdge(se->a, se->b);
@@ -973,7 +973,7 @@ void HpglFileWriter::FinishAndCloseFile(void) {
 // not self-intersecting, so not much to do.
 //-----------------------------------------------------------------------------
 void SolveSpace::ExportMeshTo(char *filename) {
-    SMesh *m = &(SS.GetGroup(SS.GW.activeGroup)->runningMesh);
+    SMesh *m = &(SK.GetGroup(SS.GW.activeGroup)->runningMesh);
     if(m->l.n == 0) {
         Error("Active group mesh is empty; nothing to export.");
         return;
diff --git a/expr.cpp b/expr.cpp
index 521f4503..6c046010 100644
--- a/expr.cpp
+++ b/expr.cpp
@@ -299,7 +299,7 @@ Expr *Expr::DeepCopyWithParamsAsPointers(IdList<Param,hParam> *firstTry,
 
 double Expr::Eval(void) {
     switch(op) {
-        case PARAM:         return SS.GetParam(x.parh)->val;
+        case PARAM:         return SK.GetParam(x.parh)->val;
         case PARAM_PTR:     return (x.parp)->val;
 
         case CONSTANT:      return x.v;
diff --git a/file.cpp b/file.cpp
index 9fe96c93..ee5a5504 100644
--- a/file.cpp
+++ b/file.cpp
@@ -14,8 +14,8 @@ hGroup SolveSpace::CreateDefaultDrawingGroup(void) {
     hRequest hr = Request::HREQUEST_REFERENCE_XY;
     g.predef.origin = hr.entity(1);
     g.name.strcpy("sketch-in-plane");
-    group.AddAndAssignId(&g);
-    SS.GetGroup(g.h)->activeWorkplane = g.h.entity(0);
+    SK.group.AddAndAssignId(&g);
+    SK.GetGroup(g.h)->activeWorkplane = g.h.entity(0);
     return g.h;
 }
 
@@ -23,12 +23,12 @@ void SolveSpace::NewFile(void) {
     UndoClearStack(&redo);
     UndoClearStack(&undo);
 
-    constraint.Clear();
-    request.Clear();
-    group.Clear();
+    SK.constraint.Clear();
+    SK.request.Clear();
+    SK.group.Clear();
 
-    entity.Clear();
-    param.Clear();
+    SK.entity.Clear();
+    SK.param.Clear();
 
     // Our initial group, that contains the references.
     Group g;
@@ -37,7 +37,7 @@ void SolveSpace::NewFile(void) {
     g.name.strcpy("#references");
     g.type = Group::DRAWING_3D;
     g.h = Group::HGROUP_REFERENCES;
-    group.Add(&g);
+    SK.group.Add(&g);
 
     // Let's create three two-d coordinate systems, for the coordinate
     // planes; these are our references, present in every sketch.
@@ -48,13 +48,13 @@ void SolveSpace::NewFile(void) {
     r.workplane = Entity::FREE_IN_3D;
 
     r.h = Request::HREQUEST_REFERENCE_XY;
-    request.Add(&r);
+    SK.request.Add(&r);
 
     r.h = Request::HREQUEST_REFERENCE_YZ;
-    request.Add(&r);
+    SK.request.Add(&r);
 
     r.h = Request::HREQUEST_REFERENCE_ZX;
-    request.Add(&r);
+    SK.request.Add(&r);
 
     CreateDefaultDrawingGroup();
 }
@@ -200,38 +200,38 @@ bool SolveSpace::SaveToFile(char *filename) {
     fprintf(fh, "%s\n\n\n", VERSION_STRING);
 
     int i;
-    for(i = 0; i < group.n; i++) {
-        sv.g = group.elem[i];
+    for(i = 0; i < SK.group.n; i++) {
+        sv.g = SK.group.elem[i];
         SaveUsingTable('g');
         fprintf(fh, "AddGroup\n\n");
     }
 
-    for(i = 0; i < param.n; i++) {
-        sv.p = param.elem[i];
+    for(i = 0; i < SK.param.n; i++) {
+        sv.p = SK.param.elem[i];
         SaveUsingTable('p');
         fprintf(fh, "AddParam\n\n");
     }
 
-    for(i = 0; i < request.n; i++) {
-        sv.r = request.elem[i];
+    for(i = 0; i < SK.request.n; i++) {
+        sv.r = SK.request.elem[i];
         SaveUsingTable('r');
         fprintf(fh, "AddRequest\n\n");
     }
 
-    for(i = 0; i < entity.n; i++) {
-        (entity.elem[i]).CalculateNumerical(true);
-        sv.e = entity.elem[i];
+    for(i = 0; i < SK.entity.n; i++) {
+        (SK.entity.elem[i]).CalculateNumerical(true);
+        sv.e = SK.entity.elem[i];
         SaveUsingTable('e');
         fprintf(fh, "AddEntity\n\n");
     }
 
-    for(i = 0; i < constraint.n; i++) {
-        sv.c = constraint.elem[i];
+    for(i = 0; i < SK.constraint.n; i++) {
+        sv.c = SK.constraint.elem[i];
         SaveUsingTable('c');
         fprintf(fh, "AddConstraint\n\n");
     }
 
-    SMesh *m = &(group.elem[group.n-1].runningMesh);
+    SMesh *m = &(SK.group.elem[SK.group.n-1].runningMesh);
     for(i = 0; i < m->l.n; i++) {
         STriangle *tr = &(m->l.elem[i]);
         fprintf(fh, "Triangle %08x %08x  "
@@ -304,11 +304,11 @@ bool SolveSpace::LoadFromFile(char *filename) {
     UndoClearStack(&redo);
     UndoClearStack(&undo);
 
-    constraint.Clear();
-    request.Clear();
-    group.Clear();
-    entity.Clear();
-    param.Clear();
+    SK.constraint.Clear();
+    SK.request.Clear();
+    SK.group.Clear();
+    SK.entity.Clear();
+    SK.param.Clear();
     memset(&sv, 0, sizeof(sv));
 
     char line[1024];
@@ -328,20 +328,20 @@ bool SolveSpace::LoadFromFile(char *filename) {
             char *key = line, *val = e+1;
             LoadUsingTable(key, val);
         } else if(strcmp(line, "AddGroup")==0) {
-            SS.group.Add(&(sv.g));
+            SK.group.Add(&(sv.g));
             memset(&(sv.g), 0, sizeof(sv.g));
         } else if(strcmp(line, "AddParam")==0) {
             // params are regenerated, but we want to preload the values
             // for initial guesses
-            SS.param.Add(&(sv.p));
+            SK.param.Add(&(sv.p));
             memset(&(sv.p), 0, sizeof(sv.p));
         } else if(strcmp(line, "AddEntity")==0) {
             // entities are regenerated
         } else if(strcmp(line, "AddRequest")==0) {
-            SS.request.Add(&(sv.r));
+            SK.request.Add(&(sv.r));
             memset(&(sv.r), 0, sizeof(sv.r));
         } else if(strcmp(line, "AddConstraint")==0) {
-            SS.constraint.Add(&(sv.c));
+            SK.constraint.Add(&(sv.c));
             memset(&(sv.c), 0, sizeof(sv.c));
         } else if(strcmp(line, VERSION_STRING)==0) {
             // do nothing, version string
@@ -420,8 +420,8 @@ void SolveSpace::ReloadAllImported(void) {
     allConsistent = false;
 
     int i;
-    for(i = 0; i < group.n; i++) {
-        Group *g = &(group.elem[i]);
+    for(i = 0; i < SK.group.n; i++) {
+        Group *g = &(SK.group.elem[i]);
         if(g->type != Group::IMPORTED) continue;
 
         g->impEntity.Clear();
diff --git a/generate.cpp b/generate.cpp
index 9984af5a..bfe08f24 100644
--- a/generate.cpp
+++ b/generate.cpp
@@ -1,15 +1,15 @@
 #include "solvespace.h"
 
 void SolveSpace::MarkGroupDirtyByEntity(hEntity he) {
-    Entity *e = SS.GetEntity(he);
+    Entity *e = SK.GetEntity(he);
     MarkGroupDirty(e->group);
 }
 
 void SolveSpace::MarkGroupDirty(hGroup hg) {
     int i;
     bool go = false;
-    for(i = 0; i < group.n; i++) {
-        Group *g = &(group.elem[i]);
+    for(i = 0; i < SK.group.n; i++) {
+        Group *g = &(SK.group.elem[i]);
         if(g->h.v == hg.v) {
             go = true;
         }
@@ -22,23 +22,23 @@ void SolveSpace::MarkGroupDirty(hGroup hg) {
 
 bool SolveSpace::PruneOrphans(void) {
     int i;
-    for(i = 0; i < request.n; i++) {
-        Request *r = &(request.elem[i]);
+    for(i = 0; i < SK.request.n; i++) {
+        Request *r = &(SK.request.elem[i]);
         if(GroupExists(r->group)) continue;
 
         (deleted.requests)++;
-        request.RemoveById(r->h);
+        SK.request.RemoveById(r->h);
         return true;
     }
 
-    for(i = 0; i < constraint.n; i++) {
-        Constraint *c = &(constraint.elem[i]);
+    for(i = 0; i < SK.constraint.n; i++) {
+        Constraint *c = &(SK.constraint.elem[i]);
         if(GroupExists(c->group)) continue;
 
         (deleted.constraints)++;
         (deleted.nonTrivialConstraints)++;
 
-        constraint.RemoveById(c->h);
+        SK.constraint.RemoveById(c->h);
         return true;
     }
     return false;
@@ -50,8 +50,8 @@ bool SolveSpace::GroupsInOrder(hGroup before, hGroup after) {
 
     int beforep = -1, afterp = -1;
     int i;
-    for(i = 0; i < group.n; i++) {
-        Group *g = &(group.elem[i]);
+    for(i = 0; i < SK.group.n; i++) {
+        Group *g = &(SK.group.elem[i]);
         if(g->h.v == before.v) beforep = i;
         if(g->h.v == after.v)  afterp  = i;
     }
@@ -62,17 +62,17 @@ bool SolveSpace::GroupsInOrder(hGroup before, hGroup after) {
 
 bool SolveSpace::GroupExists(hGroup hg) {
     // A nonexistent group is not acceptable
-    return group.FindByIdNoOops(hg) ? true : false;
+    return SK.group.FindByIdNoOops(hg) ? true : false;
 }
 bool SolveSpace::EntityExists(hEntity he) {
     // A nonexstient entity is acceptable, though, usually just means it
     // doesn't apply.
     if(he.v == Entity::NO_ENTITY.v) return true;
-    return entity.FindByIdNoOops(he) ? true : false;
+    return SK.entity.FindByIdNoOops(he) ? true : false;
 }
 
 bool SolveSpace::PruneGroups(hGroup hg) {
-    Group *g = GetGroup(hg);
+    Group *g = SK.GetGroup(hg);
     if(GroupsInOrder(g->opA, hg) &&
        EntityExists(g->predef.origin) &&
        EntityExists(g->predef.entityB) &&
@@ -81,14 +81,14 @@ bool SolveSpace::PruneGroups(hGroup hg) {
         return false;
     }
     (deleted.groups)++;
-    group.RemoveById(g->h);
+    SK.group.RemoveById(g->h);
     return true;
 }
 
 bool SolveSpace::PruneRequests(hGroup hg) {
     int i;
-    for(i = 0; i < entity.n; i++) {
-        Entity *e = &(entity.elem[i]);
+    for(i = 0; i < SK.entity.n; i++) {
+        Entity *e = &(SK.entity.elem[i]);
         if(e->group.v != hg.v) continue;
 
         if(EntityExists(e->workplane)) continue;
@@ -96,7 +96,7 @@ bool SolveSpace::PruneRequests(hGroup hg) {
         if(!e->h.isFromRequest()) oops();
 
         (deleted.requests)++;
-        request.RemoveById(e->h.request());
+        SK.request.RemoveById(e->h.request());
         return true;
     }
     return false;
@@ -104,8 +104,8 @@ bool SolveSpace::PruneRequests(hGroup hg) {
 
 bool SolveSpace::PruneConstraints(hGroup hg) {
     int i;
-    for(i = 0; i < constraint.n; i++) {
-        Constraint *c = &(constraint.elem[i]);
+    for(i = 0; i < SK.constraint.n; i++) {
+        Constraint *c = &(SK.constraint.elem[i]);
         if(c->group.v != hg.v) continue;
 
         if(EntityExists(c->workplane) &&
@@ -127,7 +127,7 @@ bool SolveSpace::PruneConstraints(hGroup hg) {
             (deleted.nonTrivialConstraints)++;
         }
 
-        constraint.RemoveById(c->h);
+        SK.constraint.RemoveById(c->h);
         return true;
     }
     return false;
@@ -138,8 +138,8 @@ void SolveSpace::GenerateAll(void) {
     int firstDirty = INT_MAX, lastVisible = 0;
     // Start from the first dirty group, and solve until the active group,
     // since all groups after the active group are hidden.
-    for(i = 0; i < group.n; i++) {
-        Group *g = &(group.elem[i]);
+    for(i = 0; i < SK.group.n; i++) {
+        Group *g = &(SK.group.elem[i]);
         g->order = i;
         if((!g->clean) || (g->solved.how != Group::SOLVED_OKAY)) {
             firstDirty = min(firstDirty, i);
@@ -167,11 +167,11 @@ void SolveSpace::GenerateAll(int first, int last, bool andFindFree) {
 
     // Don't lose our numerical guesses when we regenerate.
     IdList<Param,hParam> prev;
-    param.MoveSelfInto(&prev);
-    entity.Clear();
+    SK.param.MoveSelfInto(&prev);
+    SK.entity.Clear();
 
-    for(i = 0; i < group.n; i++) {
-        Group *g = &(group.elem[i]);
+    for(i = 0; i < SK.group.n; i++) {
+        Group *g = &(SK.group.elem[i]);
 
         // The group may depend on entities or other groups, to define its
         // workplane geometry or for its operands. Those must already exist
@@ -179,13 +179,13 @@ void SolveSpace::GenerateAll(int first, int last, bool andFindFree) {
         if(PruneGroups(g->h))
             goto pruned;
 
-        for(j = 0; j < request.n; j++) {
-            Request *r = &(request.elem[j]);
+        for(j = 0; j < SK.request.n; j++) {
+            Request *r = &(SK.request.elem[j]);
             if(r->group.v != g->h.v) continue;
 
-            r->Generate(&entity, &param);
+            r->Generate(&(SK.entity), &(SK.param));
         }
-        g->Generate(&entity, &param);
+        g->Generate(&(SK.entity), &(SK.param));
 
         // The requests and constraints depend on stuff in this or the
         // previous group, so check them after generating.
@@ -194,8 +194,8 @@ void SolveSpace::GenerateAll(int first, int last, bool andFindFree) {
 
         // Use the previous values for params that we've seen before, as
         // initial guesses for the solver.
-        for(j = 0; j < param.n; j++) {
-            Param *newp = &(param.elem[j]);
+        for(j = 0; j < SK.param.n; j++) {
+            Param *newp = &(SK.param.elem[j]);
             if(newp->known) continue;
 
             Param *prevp = prev.FindByIdNoOops(newp->h);
@@ -218,8 +218,8 @@ void SolveSpace::GenerateAll(int first, int last, bool andFindFree) {
                 // The group falls outside the range, so just assume that
                 // it's good wherever we left it. The mesh is unchanged,
                 // and the parameters must be marked as known.
-                for(j = 0; j < param.n; j++) {
-                    Param *newp = &(param.elem[j]);
+                for(j = 0; j < SK.param.n; j++) {
+                    Param *newp = &(SK.param.elem[j]);
 
                     Param *prevp = prev.FindByIdNoOops(newp->h);
                     if(prevp) newp->known = true;
@@ -229,20 +229,20 @@ void SolveSpace::GenerateAll(int first, int last, bool andFindFree) {
     }
 
     // And update any reference dimensions with their new values
-    for(i = 0; i < constraint.n; i++) {
-        Constraint *c = &(constraint.elem[i]);
+    for(i = 0; i < SK.constraint.n; i++) {
+        Constraint *c = &(SK.constraint.elem[i]);
         if(c->reference) {
             c->ModifyToSatisfy();
         }
     }
 
     // Make sure the point that we're tracing exists.
-    if(traced.point.v && !entity.FindByIdNoOops(traced.point)) {
+    if(traced.point.v && !SK.entity.FindByIdNoOops(traced.point)) {
         traced.point = Entity::NO_ENTITY;
     }
     // And if we're tracing a point, add its new value to the path
     if(traced.point.v) {
-        Entity *pt = GetEntity(traced.point);
+        Entity *pt = SK.GetEntity(traced.point);
         traced.path.AddPoint(pt->PointGetNum());
     }
 
@@ -294,8 +294,8 @@ void SolveSpace::GenerateAll(int first, int last, bool andFindFree) {
 
 pruned:
     // Restore the numerical guesses
-    param.Clear();
-    prev.MoveSelfInto(&param);
+    SK.param.Clear();
+    prev.MoveSelfInto(&(SK.param));
     // Try again
     GenerateAll(first, last);
 }
@@ -313,20 +313,20 @@ void SolveSpace::ForceReferences(void) {
     };
     for(int i = 0; i < 3; i++) {
         hRequest hr = Quat[i].hr;
-        Entity *wrkpl = GetEntity(hr.entity(0));
+        Entity *wrkpl = SK.GetEntity(hr.entity(0));
         // The origin for our coordinate system, always zero
-        Entity *origin = GetEntity(wrkpl->point[0]);
+        Entity *origin = SK.GetEntity(wrkpl->point[0]);
         origin->PointForceTo(Vector::From(0, 0, 0));
-        GetParam(origin->param[0])->known = true;
-        GetParam(origin->param[1])->known = true;
-        GetParam(origin->param[2])->known = true;
+        SK.GetParam(origin->param[0])->known = true;
+        SK.GetParam(origin->param[1])->known = true;
+        SK.GetParam(origin->param[2])->known = true;
         // The quaternion that defines the rotation, from the table.
-        Entity *normal = GetEntity(wrkpl->normal); 
+        Entity *normal = SK.GetEntity(wrkpl->normal); 
         normal->NormalForceTo(Quat[i].q);
-        GetParam(normal->param[0])->known = true;
-        GetParam(normal->param[1])->known = true;
-        GetParam(normal->param[2])->known = true;
-        GetParam(normal->param[3])->known = true;
+        SK.GetParam(normal->param[0])->known = true;
+        SK.GetParam(normal->param[1])->known = true;
+        SK.GetParam(normal->param[2])->known = true;
+        SK.GetParam(normal->param[3])->known = true;
     }
 }
 
@@ -337,20 +337,20 @@ void SolveSpace::SolveGroup(hGroup hg, bool andFindFree) {
     sys.param.Clear();
     sys.eq.Clear();
     // And generate all the params for requests in this group
-    for(i = 0; i < request.n; i++) {
-        Request *r = &(request.elem[i]);
+    for(i = 0; i < SK.request.n; i++) {
+        Request *r = &(SK.request.elem[i]);
         if(r->group.v != hg.v) continue;
 
         r->Generate(&(sys.entity), &(sys.param));
     }
     // And for the group itself
-    Group *g = SS.GetGroup(hg);
+    Group *g = SK.GetGroup(hg);
     g->Generate(&(sys.entity), &(sys.param));
     // Set the initial guesses for all the params
     for(i = 0; i < sys.param.n; i++) {
         Param *p = &(sys.param.elem[i]);
         p->known = false;
-        p->val = GetParam(p->h)->val;
+        p->val = SK.GetParam(p->h)->val;
     }
 
     sys.Solve(g, andFindFree);
@@ -360,8 +360,8 @@ void SolveSpace::SolveGroup(hGroup hg, bool andFindFree) {
 bool SolveSpace::AllGroupsOkay(void) {
     int i;
     bool allOk = true;
-    for(i = 0; i < group.n; i++) {
-        if(group.elem[i].solved.how != Group::SOLVED_OKAY) {
+    for(i = 0; i < SK.group.n; i++) {
+        if(SK.group.elem[i].solved.how != Group::SOLVED_OKAY) {
             allOk = false;
         }
     }
diff --git a/glhelper.cpp b/glhelper.cpp
index 2936ffb7..8f5f93dc 100644
--- a/glhelper.cpp
+++ b/glhelper.cpp
@@ -302,6 +302,13 @@ void glxDrawEdges(SEdgeList *el)
         glxVertex3v(se->b);
     }
     glEnd();
+    glPointSize(12);
+    glBegin(GL_POINTS);
+    for(se = el->l.First(); se; se = el->l.NextAfter(se)) {
+        glxVertex3v(se->a);
+        glxVertex3v(se->b);
+    }
+    glEnd();
 }
 
 void glxDebugMesh(SMesh *m)
diff --git a/graphicswin.cpp b/graphicswin.cpp
index dbaf69f7..7d4cf983 100644
--- a/graphicswin.cpp
+++ b/graphicswin.cpp
@@ -136,8 +136,8 @@ void GraphicsWindow::Init(void) {
     orig.projUp = projUp;
 
     // And with the last group active
-    activeGroup = SS.group.elem[SS.group.n-1].h;
-    SS.GetGroup(activeGroup)->Activate();
+    activeGroup = SK.group.elem[SK.group.n-1].h;
+    SK.GetGroup(activeGroup)->Activate();
 
     showWorkplanes = false;
     showNormals = true;
@@ -201,9 +201,9 @@ Vector GraphicsWindow::ProjectPoint4(Vector p, double *w) {
 void GraphicsWindow::AnimateOntoWorkplane(void) {
     if(!LockedInWorkplane()) return;
 
-    Entity *w = SS.GetEntity(ActiveWorkplane());
+    Entity *w = SK.GetEntity(ActiveWorkplane());
     Quaternion quatf = w->Normal()->NormalGetNum();
-    Vector offsetf = (SS.GetEntity(w->point[0])->PointGetNum()).ScaledBy(-1);
+    Vector offsetf = (SK.GetEntity(w->point[0])->PointGetNum()).ScaledBy(-1);
 
     AnimateOnto(quatf, offsetf);
 }
@@ -268,8 +268,8 @@ void GraphicsWindow::LoopOverPoints(
     HandlePointForZoomToFit(Vector::From(0, 0, 0), pmax, pmin, wmin, div);
 
     int i, j;
-    for(i = 0; i < SS.entity.n; i++) {
-        Entity *e = &(SS.entity.elem[i]);
+    for(i = 0; i < SK.entity.n; i++) {
+        Entity *e = &(SK.entity.elem[i]);
         if(!e->IsVisible()) continue;
         if(e->IsPoint()) {
             HandlePointForZoomToFit(e->PointGetNum(), pmax, pmin, wmin, div);
@@ -279,8 +279,8 @@ void GraphicsWindow::LoopOverPoints(
             // reasonable without the mesh, because a zoom to fit is used to
             // set the zoom level to set the chord tol.
             double r = e->CircleGetRadiusNum();
-            Vector c = SS.GetEntity(e->point[0])->PointGetNum();
-            Quaternion q = SS.GetEntity(e->normal)->NormalGetNum();
+            Vector c = SK.GetEntity(e->point[0])->PointGetNum();
+            Quaternion q = SK.GetEntity(e->normal)->NormalGetNum();
             for(j = 0; j < 4; j++) {
                 Vector p = (j == 0) ? (c.Plus(q.RotationU().ScaledBy( r))) :
                            (j == 1) ? (c.Plus(q.RotationU().ScaledBy(-r))) :
@@ -290,7 +290,7 @@ void GraphicsWindow::LoopOverPoints(
             }
         }
     }
-    Group *g = SS.GetGroup(activeGroup);
+    Group *g = SK.GetGroup(activeGroup);
     for(i = 0; i < g->runningMesh.l.n; i++) {
         STriangle *tr = &(g->runningMesh.l.elem[i]);
         HandlePointForZoomToFit(tr->a, pmax, pmin, wmin, div);
@@ -420,7 +420,7 @@ void GraphicsWindow::MenuView(int id) {
             if(SS.GW.gs.n == 1 && SS.GW.gs.points == 1) {
                 Quaternion quat0;
                 // Offset is the selected point, quaternion is same as before
-                Vector pt = SS.GetEntity(SS.GW.gs.point[0])->PointGetNum();
+                Vector pt = SK.GetEntity(SS.GW.gs.point[0])->PointGetNum();
                 quat0 = Quaternion::From(SS.GW.projRight, SS.GW.projUp);
                 SS.GW.AnimateOnto(quat0, pt.ScaledBy(-1));
                 SS.GW.ClearSelection();
@@ -461,15 +461,15 @@ void GraphicsWindow::MenuView(int id) {
 void GraphicsWindow::EnsureValidActives(void) {
     bool change = false;
     // The active group must exist, and not be the references.
-    Group *g = SS.group.FindByIdNoOops(activeGroup);
+    Group *g = SK.group.FindByIdNoOops(activeGroup);
     if((!g) || (g->h.v == Group::HGROUP_REFERENCES.v)) {
         int i;
-        for(i = 0; i < SS.group.n; i++) {
-            if(SS.group.elem[i].h.v != Group::HGROUP_REFERENCES.v) {
+        for(i = 0; i < SK.group.n; i++) {
+            if(SK.group.elem[i].h.v != Group::HGROUP_REFERENCES.v) {
                 break;
             }
         }
-        if(i >= SS.group.n) {
+        if(i >= SK.group.n) {
             // This can happen if the user deletes all the groups in the
             // sketch. It's difficult to prevent that, because the last
             // group might have been deleted automatically, because it failed
@@ -478,15 +478,15 @@ void GraphicsWindow::EnsureValidActives(void) {
             // to delete the references, though.
             activeGroup = SS.CreateDefaultDrawingGroup();
         } else {
-            activeGroup = SS.group.elem[i].h;
+            activeGroup = SK.group.elem[i].h;
         }
-        SS.GetGroup(activeGroup)->Activate();
+        SK.GetGroup(activeGroup)->Activate();
         change = true;
     }
 
     // The active coordinate system must also exist.
     if(LockedInWorkplane()) {
-        Entity *e = SS.entity.FindByIdNoOops(ActiveWorkplane());
+        Entity *e = SK.entity.FindByIdNoOops(ActiveWorkplane());
         if(e) {
             hGroup hgw = e->group;
             if(hgw.v != activeGroup.v && SS.GroupsInOrder(activeGroup, hgw)) {
@@ -527,10 +527,10 @@ void GraphicsWindow::EnsureValidActives(void) {
 }
 
 void GraphicsWindow::SetWorkplaneFreeIn3d(void) {
-    SS.GetGroup(activeGroup)->activeWorkplane = Entity::FREE_IN_3D;
+    SK.GetGroup(activeGroup)->activeWorkplane = Entity::FREE_IN_3D;
 }
 hEntity GraphicsWindow::ActiveWorkplane(void) {
-    Group *g = SS.group.FindByIdNoOops(activeGroup);
+    Group *g = SK.group.FindByIdNoOops(activeGroup);
     if(g) {
         return g->activeWorkplane;
     } else {
@@ -550,7 +550,7 @@ void GraphicsWindow::ForceTextWindowShown(void) {
 }
 
 void GraphicsWindow::DeleteTaggedRequests(void) {
-    SS.request.RemoveTagged();
+    SK.request.RemoveTagged();
 
     // An edit might be in progress for the just-deleted item. So
     // now it's not.
@@ -583,8 +583,8 @@ void GraphicsWindow::MenuEdit(int id) {
             SS.UndoRemember();
 
             int i;
-            SS.request.ClearTags();
-            SS.constraint.ClearTags();
+            SK.request.ClearTags();
+            SK.constraint.ClearTags();
             for(i = 0; i < MAX_SELECTED; i++) {
                 Selection *s = &(SS.GW.selection[i]);
                 hRequest r; r.v = 0;
@@ -592,14 +592,14 @@ void GraphicsWindow::MenuEdit(int id) {
                     r = s->entity.request();
                 }
                 if(r.v && !r.IsFromReferences()) {
-                    SS.request.Tag(r, 1);
+                    SK.request.Tag(r, 1);
                 }
                 if(s->constraint.v) {
-                    SS.constraint.Tag(s->constraint, 1);
+                    SK.constraint.Tag(s->constraint, 1);
                 }
             }
 
-            SS.constraint.RemoveTagged();
+            SK.constraint.RemoveTagged();
             SS.GW.DeleteTaggedRequests();
             break;
         }
@@ -627,7 +627,7 @@ void GraphicsWindow::MenuRequest(int id) {
     switch(id) {
         case MNU_SEL_WORKPLANE: {
             SS.GW.GroupSelection();
-            Group *g = SS.GetGroup(SS.GW.activeGroup);
+            Group *g = SK.GetGroup(SS.GW.activeGroup);
 
             if(SS.GW.gs.n == 1 && SS.GW.gs.workplanes == 1) {
                 // A user-selected workplane
@@ -683,7 +683,7 @@ c:
             for(i = 0; i < SS.GW.gs.entities; i++) {
                 hEntity he = SS.GW.gs.entity[i];
                 if(!he.isFromRequest()) continue;
-                Request *r = SS.GetRequest(he.request());
+                Request *r = SK.GetRequest(he.request());
                 r->construction = !(r->construction);
                 SS.MarkGroupDirty(r->group);
             }
diff --git a/group.cpp b/group.cpp
index 536ffde2..85b9ff70 100644
--- a/group.cpp
+++ b/group.cpp
@@ -17,7 +17,7 @@ void Group::AddParam(IdList<Param,hParam> *param, hParam hp, double v) {
 }
 
 void Group::MenuGroup(int id) {
-    if(!SS.license.licensed && SS.group.n >= 7) {
+    if(!SS.license.licensed && SK.group.n >= 7) {
         Error("The free version of this software does not support more "
               "than six groups.\r\n\r\n"
               "To remove this restriction, please choose Help -> "
@@ -63,8 +63,8 @@ void Group::MenuGroup(int id) {
                 g.predef.entityB = gs.entity[0];
                 g.predef.entityC = gs.entity[1];
 
-                Vector ut = SS.GetEntity(g.predef.entityB)->VectorGetNum();
-                Vector vt = SS.GetEntity(g.predef.entityC)->VectorGetNum();
+                Vector ut = SK.GetEntity(g.predef.entityB)->VectorGetNum();
+                Vector vt = SK.GetEntity(g.predef.entityC)->VectorGetNum();
                 ut = ut.WithMagnitude(1);
                 vt = vt.WithMagnitude(1);
 
@@ -98,7 +98,7 @@ void Group::MenuGroup(int id) {
                 g.predef.origin = gs.point[0];
                 g.predef.entityB = gs.vector[0];
             } else if(gs.lineSegments == 1 && gs.n == 1) {
-                g.predef.origin = SS.GetEntity(gs.entity[0])->point[0];
+                g.predef.origin = SK.GetEntity(gs.entity[0])->point[0];
                 g.predef.entityB = gs.entity[0];
                 // since a line segment is a vector
             } else {
@@ -120,14 +120,14 @@ void Group::MenuGroup(int id) {
             // Get the group one before the active group; that's our
             // trajectory
             int i;
-            for(i = 1; i < SS.group.n - 1; i++) {
-                Group *gnext = &(SS.group.elem[i+1]);
+            for(i = 1; i < SK.group.n - 1; i++) {
+                Group *gnext = &(SK.group.elem[i+1]);
                 if(gnext->h.v == SS.GW.activeGroup.v) {
-                    g.opA = SS.group.elem[i].h;
+                    g.opA = SK.group.elem[i].h;
                     break;
                 }
             }
-            if(i >= SS.group.n - 1) {
+            if(i >= SK.group.n - 1) {
                 Error("At least one sketch before the active sketch must "
                       "exist; that specifies the sweep trajectory.");
                 return;
@@ -140,10 +140,10 @@ void Group::MenuGroup(int id) {
 
         case GraphicsWindow::MNU_GROUP_HELICAL: {
             if(gs.points == 1 && gs.lineSegments == 1 && gs.n == 2) {
-                Vector pt = SS.GetEntity(gs.point[0])->PointGetNum();
-                Entity *ln = SS.GetEntity(gs.entity[0]);
-                Vector lpa = SS.GetEntity(ln->point[0])->PointGetNum();
-                Vector lpb = SS.GetEntity(ln->point[1])->PointGetNum();
+                Vector pt = SK.GetEntity(gs.point[0])->PointGetNum();
+                Entity *ln = SK.GetEntity(gs.entity[0]);
+                Vector lpa = SK.GetEntity(ln->point[0])->PointGetNum();
+                Vector lpb = SK.GetEntity(ln->point[1])->PointGetNum();
                 double d = pt.DistanceToLine(lpa, lpb.Minus(lpa));
                 if(d < LENGTH_EPS) {
                     Error("Point on helix can't lie on helix's axis!");
@@ -171,7 +171,7 @@ void Group::MenuGroup(int id) {
         case GraphicsWindow::MNU_GROUP_ROT: {
             if(gs.points == 1 && gs.n == 1 && SS.GW.LockedInWorkplane()) {
                 g.predef.origin = gs.point[0];
-                Entity *w = SS.GetEntity(SS.GW.ActiveWorkplane());
+                Entity *w = SK.GetEntity(SS.GW.ActiveWorkplane());
                 g.predef.entityB = w->Normal()->h;
                 g.activeWorkplane = w->h;
             } else if(gs.points == 1 && gs.vectors == 1 && gs.n == 2) {
@@ -220,8 +220,8 @@ void Group::MenuGroup(int id) {
     SS.GW.ClearSelection();
     SS.UndoRemember();
 
-    SS.group.AddAndAssignId(&g);
-    Group *gg = SS.GetGroup(g.h);
+    SK.group.AddAndAssignId(&g);
+    Group *gg = SK.GetGroup(g.h);
 
     if(gg->type == IMPORTED) {
         SS.ReloadAllImported();
@@ -277,8 +277,8 @@ void Group::Generate(IdList<Entity,hEntity> *entity,
         case DRAWING_WORKPLANE: {
             Quaternion q;
             if(subtype == WORKPLANE_BY_LINE_SEGMENTS) {
-                Vector u = SS.GetEntity(predef.entityB)->VectorGetNum();
-                Vector v = SS.GetEntity(predef.entityC)->VectorGetNum();
+                Vector u = SK.GetEntity(predef.entityB)->VectorGetNum();
+                Vector v = SK.GetEntity(predef.entityC)->VectorGetNum();
                 u = u.WithMagnitude(1);
                 Vector n = u.Cross(v);
                 v = (n.Cross(u)).WithMagnitude(1);
@@ -304,7 +304,7 @@ void Group::Generate(IdList<Entity,hEntity> *entity,
             Entity point;
             memset(&point, 0, sizeof(point));
             point.type = Entity::POINT_N_COPY;
-            point.numPoint = SS.GetEntity(predef.origin)->PointGetNum();
+            point.numPoint = SK.GetEntity(predef.origin)->PointGetNum();
             point.group = h;
             point.h = h.entity(2);
             entity->Add(&point);
@@ -344,11 +344,11 @@ void Group::Generate(IdList<Entity,hEntity> *entity,
                 hEntity he = e->h; e = NULL;
                 // As soon as I call CopyEntity, e may become invalid! That
                 // adds entities, which may cause a realloc.
-                CopyEntity(entity, SS.GetEntity(he), ai, REMAP_BOTTOM,
+                CopyEntity(entity, SK.GetEntity(he), ai, REMAP_BOTTOM,
                     h.param(0), h.param(1), h.param(2),
                     NO_PARAM, NO_PARAM, NO_PARAM, NO_PARAM,
                     true, false);
-                CopyEntity(entity, SS.GetEntity(he), af, REMAP_TOP,
+                CopyEntity(entity, SK.GetEntity(he), af, REMAP_TOP,
                     h.param(0), h.param(1), h.param(2),
                     NO_PARAM, NO_PARAM, NO_PARAM, NO_PARAM,
                     true, false);
@@ -477,12 +477,12 @@ void Group::GenerateEquations(IdList<Equation,hEquation> *l) {
         // The axis and center of rotation are specified numerically
 #define EC(x) (Expr::From(x))
 #define EP(x) (Expr::From(h.param(x)))
-        ExprVector orig = SS.GetEntity(predef.origin)->PointGetExprs();
+        ExprVector orig = SK.GetEntity(predef.origin)->PointGetExprs();
         AddEq(l, (orig.x)->Minus(EP(0)), 0);
         AddEq(l, (orig.y)->Minus(EP(1)), 1);
         AddEq(l, (orig.z)->Minus(EP(2)), 2);
         // param 3 is the angle, which is free
-        Vector axis = SS.GetEntity(predef.entityB)->VectorGetNum();
+        Vector axis = SK.GetEntity(predef.entityB)->VectorGetNum();
         axis = axis.WithMagnitude(1);
         AddEq(l, (EC(axis.x))->Minus(EP(4)), 3);
         AddEq(l, (EC(axis.y))->Minus(EP(5)), 4);
@@ -491,7 +491,7 @@ void Group::GenerateEquations(IdList<Equation,hEquation> *l) {
         if(predef.entityB.v != Entity::FREE_IN_3D.v) {
             // The extrusion path is locked along a line, normal to the
             // specified workplane.
-            Entity *w = SS.GetEntity(predef.entityB);
+            Entity *w = SK.GetEntity(predef.entityB);
             ExprVector u = w->Normal()->NormalExprsU();
             ExprVector v = w->Normal()->NormalExprsV();
             ExprVector extruden = {
@@ -504,7 +504,7 @@ void Group::GenerateEquations(IdList<Equation,hEquation> *l) {
         }
     } else if(type == TRANSLATE) {
         if(predef.entityB.v != Entity::FREE_IN_3D.v) {
-            Entity *w = SS.GetEntity(predef.entityB);
+            Entity *w = SK.GetEntity(predef.entityB);
             ExprVector n = w->Normal()->NormalExprsN();
             ExprVector trans;
             trans = ExprVector::From(h.param(0), h.param(1), h.param(2));
@@ -543,7 +543,7 @@ hEntity Group::Remap(hEntity in, int copyNumber) {
 }
 
 void Group::MakeExtrusionLines(IdList<Entity,hEntity> *el, hEntity in) {
-    Entity *ep = SS.GetEntity(in);
+    Entity *ep = SK.GetEntity(in);
 
     Entity en;
     ZERO(&en);
@@ -558,8 +558,8 @@ void Group::MakeExtrusionLines(IdList<Entity,hEntity> *el, hEntity in) {
     } else if(ep->type == Entity::LINE_SEGMENT) {
         // A line gets extruded to form a plane face; an endpoint of the
         // original line is a point in the plane, and the line is in the plane.
-        Vector a = SS.GetEntity(ep->point[0])->PointGetNum();
-        Vector b = SS.GetEntity(ep->point[1])->PointGetNum();
+        Vector a = SK.GetEntity(ep->point[0])->PointGetNum();
+        Vector b = SK.GetEntity(ep->point[1])->PointGetNum();
         Vector ab = b.Minus(a);
 
         en.param[0] = h.param(0);
@@ -578,7 +578,7 @@ void Group::MakeExtrusionLines(IdList<Entity,hEntity> *el, hEntity in) {
 void Group::MakeExtrusionTopBottomFaces(IdList<Entity,hEntity> *el, hEntity pt)
 {
     if(pt.v == 0) return;
-    Group *src = SS.GetGroup(opA);
+    Group *src = SK.GetGroup(opA);
     Vector n = src->poly.normal;
 
     Entity en;
@@ -742,13 +742,13 @@ void Group::CopyEntity(IdList<Entity,hEntity> *el,
 
 void Group::TagEdgesFromLineSegments(SEdgeList *el) {
     int i, j;
-    for(i = 0; i < SS.entity.n; i++) {
-        Entity *e = &(SS.entity.elem[i]);
+    for(i = 0; i < SK.entity.n; i++) {
+        Entity *e = &(SK.entity.elem[i]);
         if(e->group.v != opA.v) continue;
         if(e->type != Entity::LINE_SEGMENT) continue;
 
-        Vector p0 = SS.GetEntity(e->point[0])->PointGetNum();
-        Vector p1 = SS.GetEntity(e->point[1])->PointGetNum();
+        Vector p0 = SK.GetEntity(e->point[0])->PointGetNum();
+        Vector p1 = SK.GetEntity(e->point[1])->PointGetNum();
         
         for(j = 0; j < el->l.n; j++) {
             SEdge *se = &(el->l.elem[j]);
diff --git a/groupmesh.cpp b/groupmesh.cpp
index 2a42521e..232fa80f 100644
--- a/groupmesh.cpp
+++ b/groupmesh.cpp
@@ -7,8 +7,8 @@ bool Group::AssembleLoops(void) {
     ZERO(&sbl);
 
     int i;
-    for(i = 0; i < SS.entity.n; i++) {
-        Entity *e = &(SS.entity.elem[i]);
+    for(i = 0; i < SK.entity.n; i++) {
+        Entity *e = &(SK.entity.elem[i]);
         if(e->group.v != h.v) continue;
         if(e->construction) continue;
 
@@ -52,7 +52,7 @@ void Group::GenerateLoops(void) {
 }
 
 void Group::GenerateShellForStepAndRepeat(void) {
-    Group *src = SS.GetGroup(opA);
+    Group *src = SK.GetGroup(opA);
     SShell *srcs = &(src->thisShell); // the shell to step and repeat
 
     SShell workA, workB;
@@ -79,7 +79,7 @@ void Group::GenerateShellForStepAndRepeat(void) {
             transd.MakeFromTransformationOf(srcs, trans, q);
         } else {
             Vector trans = Vector::From(h.param(0), h.param(1), h.param(2));
-            double theta = ap * SS.GetParam(h.param(3))->val;
+            double theta = ap * SK.GetParam(h.param(3))->val;
             double c = cos(theta), s = sin(theta);
             Vector axis = Vector::From(h.param(4), h.param(5), h.param(6));
             Quaternion q = Quaternion::From(c, s*axis.x, s*axis.y, s*axis.z);
@@ -122,7 +122,7 @@ void Group::GenerateShellAndMesh(void) {
     }
 
     if(type == EXTRUDE) {
-        Group *src = SS.GetGroup(opA);
+        Group *src = SK.GetGroup(opA);
         Vector translate = Vector::From(h.param(0), h.param(1), h.param(2));
 
         Vector tbot, ttop;
@@ -162,12 +162,12 @@ void Group::GenerateShellAndMesh(void) {
             if(ss->degm != 1 || ss->degn != 1) continue;
 
             Entity *e;
-            for(e = SS.entity.First(); e; e = SS.entity.NextAfter(e)) {
+            for(e = SK.entity.First(); e; e = SK.entity.NextAfter(e)) {
                 if(e->group.v != opA.v) continue;
                 if(e->type != Entity::LINE_SEGMENT) continue;
 
-                Vector a = SS.GetEntity(e->point[0])->PointGetNum(),
-                       b = SS.GetEntity(e->point[1])->PointGetNum();
+                Vector a = SK.GetEntity(e->point[0])->PointGetNum(),
+                       b = SK.GetEntity(e->point[1])->PointGetNum();
                 a = a.Plus(ttop);
                 b = b.Plus(ttop);
                 // Could get taken backwards, so check all cases.
@@ -183,24 +183,24 @@ void Group::GenerateShellAndMesh(void) {
             }
         }
     } else if(type == LATHE) {
-        Group *src = SS.GetGroup(opA);
+        Group *src = SK.GetGroup(opA);
 
-        Vector orig = SS.GetEntity(predef.origin)->PointGetNum();
-        Vector axis = SS.GetEntity(predef.entityB)->VectorGetNum();
+        Vector orig = SK.GetEntity(predef.origin)->PointGetNum();
+        Vector axis = SK.GetEntity(predef.entityB)->VectorGetNum();
         axis = axis.WithMagnitude(1);
 
     } else if(type == IMPORTED) {
         // Triangles are just copied over, with the appropriate transformation
         // applied.
         Vector offset = {
-            SS.GetParam(h.param(0))->val,
-            SS.GetParam(h.param(1))->val,
-            SS.GetParam(h.param(2))->val };
+            SK.GetParam(h.param(0))->val,
+            SK.GetParam(h.param(1))->val,
+            SK.GetParam(h.param(2))->val };
         Quaternion q = {
-            SS.GetParam(h.param(3))->val,
-            SS.GetParam(h.param(4))->val,
-            SS.GetParam(h.param(5))->val,
-            SS.GetParam(h.param(6))->val };
+            SK.GetParam(h.param(3))->val,
+            SK.GetParam(h.param(4))->val,
+            SK.GetParam(h.param(5))->val,
+            SK.GetParam(h.param(6))->val };
 
         for(int i = 0; i < impMesh.l.n; i++) {
             STriangle st = impMesh.l.elem[i];
@@ -245,12 +245,12 @@ done:
 
 SShell *Group::PreviousGroupShell(void) {
     int i;
-    for(i = 0; i < SS.group.n; i++) {
-        Group *g = &(SS.group.elem[i]);
+    for(i = 0; i < SK.group.n; i++) {
+        Group *g = &(SK.group.elem[i]);
         if(g->h.v == h.v) break;
     }
-    if(i == 0 || i >= SS.group.n) oops();
-    return &(SS.group.elem[i-1].runningShell);
+    if(i == 0 || i >= SK.group.n) oops();
+    return &(SK.group.elem[i-1].runningShell);
 }
 
 void Group::Draw(void) {
@@ -272,7 +272,7 @@ void Group::Draw(void) {
     // or hovered, in order to draw them differently.
     DWORD mh = 0, ms1 = 0, ms2 = 0;
     hEntity he = SS.GW.hover.entity;
-    if(he.v != 0 && SS.GetEntity(he)->IsFace()) {
+    if(he.v != 0 && SK.GetEntity(he)->IsFace()) {
         mh = he.v;
     }
     SS.GW.GroupSelection();
diff --git a/modify.cpp b/modify.cpp
index 1ea32a5a..b67b89c2 100644
--- a/modify.cpp
+++ b/modify.cpp
@@ -6,8 +6,8 @@
 //-----------------------------------------------------------------------------
 void GraphicsWindow::ReplacePointInConstraints(hEntity oldpt, hEntity newpt) {
     int i;
-    for(i = 0; i < SS.constraint.n; i++) {
-        Constraint *c = &(SS.constraint.elem[i]);
+    for(i = 0; i < SK.constraint.n; i++) {
+        Constraint *c = &(SK.constraint.elem[i]);
 
         if(c->type == Constraint::POINTS_COINCIDENT) {
             if(c->ptA.v == oldpt.v) c->ptA = newpt;
@@ -31,22 +31,22 @@ void GraphicsWindow::MakeTangentArc(void) {
     // Find two line segments that join at the specified point,
     // and blend them with a tangent arc. First, find the
     // requests that generate the line segments.
-    Vector pshared = SS.GetEntity(gs.point[0])->PointGetNum();
+    Vector pshared = SK.GetEntity(gs.point[0])->PointGetNum();
     ClearSelection();
 
     int i, c = 0;
     Entity *line[2];
     Request *lineReq[2];
     bool point1[2];
-    for(i = 0; i < SS.request.n; i++) {
-        Request *r = &(SS.request.elem[i]);
+    for(i = 0; i < SK.request.n; i++) {
+        Request *r = &(SK.request.elem[i]);
         if(r->group.v != activeGroup.v) continue;
         if(r->type != Request::LINE_SEGMENT) continue;
         if(r->construction) continue;
 
-        Entity *e = SS.GetEntity(r->h.entity(0));
-        Vector p0 = SS.GetEntity(e->point[0])->PointGetNum(),
-               p1 = SS.GetEntity(e->point[1])->PointGetNum();
+        Entity *e = SK.GetEntity(r->h.entity(0));
+        Vector p0 = SK.GetEntity(e->point[0])->PointGetNum(),
+               p1 = SK.GetEntity(e->point[1])->PointGetNum();
         
         if(p0.Equals(pshared) || p1.Equals(pshared)) {
             if(c < 2) {
@@ -65,15 +65,15 @@ void GraphicsWindow::MakeTangentArc(void) {
 
     SS.UndoRemember();
 
-    Entity *wrkpl = SS.GetEntity(ActiveWorkplane());
+    Entity *wrkpl = SK.GetEntity(ActiveWorkplane());
     Vector wn = wrkpl->Normal()->NormalN();
 
     hEntity hshared = (line[0])->point[point1[0] ? 1 : 0],
             hother0 = (line[0])->point[point1[0] ? 0 : 1],
             hother1 = (line[1])->point[point1[1] ? 0 : 1];
 
-    Vector pother0 = SS.GetEntity(hother0)->PointGetNum(),
-           pother1 = SS.GetEntity(hother1)->PointGetNum();
+    Vector pother0 = SK.GetEntity(hother0)->PointGetNum(),
+           pother1 = SK.GetEntity(hother1)->PointGetNum();
 
     Vector v0shared = pshared.Minus(pother0),
            v1shared = pshared.Minus(pother1);
@@ -109,21 +109,21 @@ void GraphicsWindow::MakeTangentArc(void) {
              rln1 = AddRequest(Request::LINE_SEGMENT, false);
     hRequest rarc = AddRequest(Request::ARC_OF_CIRCLE, false);
 
-    Entity *ln0 = SS.GetEntity(rln0.entity(0)),
-           *ln1 = SS.GetEntity(rln1.entity(0));
-    Entity *arc = SS.GetEntity(rarc.entity(0));
+    Entity *ln0 = SK.GetEntity(rln0.entity(0)),
+           *ln1 = SK.GetEntity(rln1.entity(0));
+    Entity *arc = SK.GetEntity(rarc.entity(0));
 
-    SS.GetEntity(ln0->point[0])->PointForceTo(pother0);
+    SK.GetEntity(ln0->point[0])->PointForceTo(pother0);
     Constraint::ConstrainCoincident(ln0->point[0], hother0);
 
-    SS.GetEntity(ln1->point[0])->PointForceTo(pother1);
+    SK.GetEntity(ln1->point[0])->PointForceTo(pother1);
     Constraint::ConstrainCoincident(ln1->point[0], hother1);
 
     Vector arc0 = pshared.Minus(v0shared.WithMagnitude(el));
     Vector arc1 = pshared.Minus(v1shared.WithMagnitude(el));
 
-    SS.GetEntity(ln0->point[1])->PointForceTo(arc0);
-    SS.GetEntity(ln1->point[1])->PointForceTo(arc1);
+    SK.GetEntity(ln0->point[1])->PointForceTo(arc0);
+    SK.GetEntity(ln1->point[1])->PointForceTo(arc1);
 
     Constraint::Constrain(Constraint::PT_ON_LINE,
         ln0->point[1], Entity::NO_ENTITY, srcline0);
@@ -140,9 +140,9 @@ void GraphicsWindow::MakeTangentArc(void) {
         center = center.Plus(v0shared.Cross(wn).WithMagnitude(r));
     }
 
-    SS.GetEntity(arc->point[0])->PointForceTo(center);
-    SS.GetEntity(arc->point[a])->PointForceTo(arc0);
-    SS.GetEntity(arc->point[b])->PointForceTo(arc1);
+    SK.GetEntity(arc->point[0])->PointForceTo(center);
+    SK.GetEntity(arc->point[a])->PointForceTo(arc0);
+    SK.GetEntity(arc->point[b])->PointForceTo(arc1);
 
     Constraint::ConstrainCoincident(arc->point[a], ln0->point[1]);
     Constraint::ConstrainCoincident(arc->point[b], ln1->point[1]);
@@ -159,10 +159,10 @@ void GraphicsWindow::MakeTangentArc(void) {
 
 void GraphicsWindow::SplitLine(hEntity he, Vector pinter) {
     // Save the original endpoints, since we're about to delete this entity.
-    Entity *e01 = SS.GetEntity(he);
+    Entity *e01 = SK.GetEntity(he);
     hEntity hep0 = e01->point[0], hep1 = e01->point[1];
-    Vector p0 = SS.GetEntity(hep0)->PointGetNum(),
-           p1 = SS.GetEntity(hep1)->PointGetNum();
+    Vector p0 = SK.GetEntity(hep0)->PointGetNum(),
+           p1 = SK.GetEntity(hep1)->PointGetNum();
 
     SS.UndoRemember();
 
@@ -171,22 +171,22 @@ void GraphicsWindow::SplitLine(hEntity he, Vector pinter) {
              ri1 = AddRequest(Request::LINE_SEGMENT, false);
     // Don't get entities till after adding, realloc issues
 
-    Entity *e0i = SS.GetEntity(r0i.entity(0)),
-           *ei1 = SS.GetEntity(ri1.entity(0));
+    Entity *e0i = SK.GetEntity(r0i.entity(0)),
+           *ei1 = SK.GetEntity(ri1.entity(0));
 
-    SS.GetEntity(e0i->point[0])->PointForceTo(p0);
-    SS.GetEntity(e0i->point[1])->PointForceTo(pinter);
-    SS.GetEntity(ei1->point[0])->PointForceTo(pinter);
-    SS.GetEntity(ei1->point[1])->PointForceTo(p1);
+    SK.GetEntity(e0i->point[0])->PointForceTo(p0);
+    SK.GetEntity(e0i->point[1])->PointForceTo(pinter);
+    SK.GetEntity(ei1->point[0])->PointForceTo(pinter);
+    SK.GetEntity(ei1->point[1])->PointForceTo(p1);
 
     ReplacePointInConstraints(hep0, e0i->point[0]);
     ReplacePointInConstraints(hep1, ei1->point[1]);
 
     // Finally, delete the original line
     int i;
-    SS.request.ClearTags();
-    for(i = 0; i < SS.request.n; i++) {
-        Request *r = &(SS.request.elem[i]);
+    SK.request.ClearTags();
+    for(i = 0; i < SK.request.n; i++) {
+        Request *r = &(SK.request.elem[i]);
         if(r->group.v != activeGroup.v) continue;
         if(r->type != Request::LINE_SEGMENT) continue;
     
@@ -203,46 +203,46 @@ void GraphicsWindow::SplitLine(hEntity he, Vector pinter) {
 void GraphicsWindow::SplitCircle(hEntity he, Vector pinter) {
     SS.UndoRemember();
 
-    Entity *circle = SS.GetEntity(he);
+    Entity *circle = SK.GetEntity(he);
     if(circle->type == Entity::CIRCLE) {
         // Start with an unbroken circle, split it into a 360 degree arc.
-        Vector center = SS.GetEntity(circle->point[0])->PointGetNum();
+        Vector center = SK.GetEntity(circle->point[0])->PointGetNum();
 
         circle = NULL; // shortly invalid!
         hRequest hr = AddRequest(Request::ARC_OF_CIRCLE, false);
 
-        Entity *arc = SS.GetEntity(hr.entity(0));
+        Entity *arc = SK.GetEntity(hr.entity(0));
 
-        SS.GetEntity(arc->point[0])->PointForceTo(center);
-        SS.GetEntity(arc->point[1])->PointForceTo(pinter);
-        SS.GetEntity(arc->point[2])->PointForceTo(pinter);
+        SK.GetEntity(arc->point[0])->PointForceTo(center);
+        SK.GetEntity(arc->point[1])->PointForceTo(pinter);
+        SK.GetEntity(arc->point[2])->PointForceTo(pinter);
     } else {
         // Start with an arc, break it in to two arcs
-        Vector center = SS.GetEntity(circle->point[0])->PointGetNum(),
-               start  = SS.GetEntity(circle->point[1])->PointGetNum(),
-               finish = SS.GetEntity(circle->point[2])->PointGetNum();
+        Vector center = SK.GetEntity(circle->point[0])->PointGetNum(),
+               start  = SK.GetEntity(circle->point[1])->PointGetNum(),
+               finish = SK.GetEntity(circle->point[2])->PointGetNum();
 
         circle = NULL; // shortly invalid!
         hRequest hr0 = AddRequest(Request::ARC_OF_CIRCLE, false),
                  hr1 = AddRequest(Request::ARC_OF_CIRCLE, false);
 
-        Entity *arc0 = SS.GetEntity(hr0.entity(0)),
-               *arc1 = SS.GetEntity(hr1.entity(0));
+        Entity *arc0 = SK.GetEntity(hr0.entity(0)),
+               *arc1 = SK.GetEntity(hr1.entity(0));
 
-        SS.GetEntity(arc0->point[0])->PointForceTo(center);
-        SS.GetEntity(arc0->point[1])->PointForceTo(start);
-        SS.GetEntity(arc0->point[2])->PointForceTo(pinter);
+        SK.GetEntity(arc0->point[0])->PointForceTo(center);
+        SK.GetEntity(arc0->point[1])->PointForceTo(start);
+        SK.GetEntity(arc0->point[2])->PointForceTo(pinter);
 
-        SS.GetEntity(arc1->point[0])->PointForceTo(center);
-        SS.GetEntity(arc1->point[1])->PointForceTo(pinter);
-        SS.GetEntity(arc1->point[2])->PointForceTo(finish);
+        SK.GetEntity(arc1->point[0])->PointForceTo(center);
+        SK.GetEntity(arc1->point[1])->PointForceTo(pinter);
+        SK.GetEntity(arc1->point[2])->PointForceTo(finish);
     }
 
     // Finally, delete the original circle or arc
     int i;
-    SS.request.ClearTags();
-    for(i = 0; i < SS.request.n; i++) {
-        Request *r = &(SS.request.elem[i]);
+    SK.request.ClearTags();
+    for(i = 0; i < SK.request.n; i++) {
+        Request *r = &(SK.request.elem[i]);
         if(r->group.v != activeGroup.v) continue;
         if(r->type != Request::CIRCLE && r->type != Request::ARC_OF_CIRCLE) {
             continue;
@@ -266,12 +266,12 @@ void GraphicsWindow::SplitLinesOrCurves(void) {
 
     GroupSelection();
     if(gs.n == 2 && gs.lineSegments == 2) {
-        Entity *la = SS.GetEntity(gs.entity[0]),
-               *lb = SS.GetEntity(gs.entity[1]);
-        Vector a0 = SS.GetEntity(la->point[0])->PointGetNum(),
-               a1 = SS.GetEntity(la->point[1])->PointGetNum(),
-               b0 = SS.GetEntity(lb->point[0])->PointGetNum(),
-               b1 = SS.GetEntity(lb->point[1])->PointGetNum();
+        Entity *la = SK.GetEntity(gs.entity[0]),
+               *lb = SK.GetEntity(gs.entity[1]);
+        Vector a0 = SK.GetEntity(la->point[0])->PointGetNum(),
+               a1 = SK.GetEntity(la->point[1])->PointGetNum(),
+               b0 = SK.GetEntity(lb->point[0])->PointGetNum(),
+               b1 = SK.GetEntity(lb->point[1])->PointGetNum();
         Vector da = a1.Minus(a0), db = b1.Minus(b0);
         
         // First, check if the lines intersect.
@@ -306,20 +306,20 @@ void GraphicsWindow::SplitLinesOrCurves(void) {
                 "Nothing to split; intersection does not lie on either line.");
         }
     } else if(gs.n == 2 && gs.lineSegments == 1 && gs.circlesOrArcs == 1) {
-        Entity *line   = SS.GetEntity(gs.entity[0]),
-               *circle = SS.GetEntity(gs.entity[1]);
+        Entity *line   = SK.GetEntity(gs.entity[0]),
+               *circle = SK.GetEntity(gs.entity[1]);
         if(line->type != Entity::LINE_SEGMENT) {
             SWAP(Entity *, line, circle);
         }
         hEntity hline = line->h, hcircle = circle->h;
 
-        Vector l0 = SS.GetEntity(line->point[0])->PointGetNum(),
-               l1 = SS.GetEntity(line->point[1])->PointGetNum();
+        Vector l0 = SK.GetEntity(line->point[0])->PointGetNum(),
+               l1 = SK.GetEntity(line->point[1])->PointGetNum();
         Vector dl = l1.Minus(l0);
 
-        Quaternion q = SS.GetEntity(circle->normal)->NormalGetNum();
+        Quaternion q = SK.GetEntity(circle->normal)->NormalGetNum();
         Vector cn = q.RotationN();
-        Vector cc = SS.GetEntity(circle->point[0])->PointGetNum();
+        Vector cc = SK.GetEntity(circle->point[0])->PointGetNum();
         double cd = cc.Dot(cn);
         double cr = circle->CircleGetRadiusNum();
 
@@ -357,8 +357,8 @@ void GraphicsWindow::SplitLinesOrCurves(void) {
             thetamin = 0;
             thetamax = 2.1*PI; // fudge, make sure it's a good complete circle
         } else {
-            Vector start  = SS.GetEntity(circle->point[1])->PointGetNum(),
-                   finish = SS.GetEntity(circle->point[2])->PointGetNum();
+            Vector start  = SK.GetEntity(circle->point[1])->PointGetNum(),
+                   finish = SK.GetEntity(circle->point[2])->PointGetNum();
             start  = (start .Minus(cc)).DotInToCsys(u, v, n);
             finish = (finish.Minus(cc)).DotInToCsys(u, v, n);
             thetamin = atan2(start.y, start.x);
diff --git a/solvespace.cpp b/solvespace.cpp
index 6c7d03e6..6cd80988 100644
--- a/solvespace.cpp
+++ b/solvespace.cpp
@@ -1,6 +1,7 @@
 #include "solvespace.h"
 
 SolveSpace SS;
+Sketch SK;
 
 void SolveSpace::CheckLicenseFromRegistry(void) {
     // First, let's see if we're running licensed or free
@@ -388,7 +389,7 @@ void SolveSpace::MenuAnalyze(int id) {
     switch(id) {
         case GraphicsWindow::MNU_STEP_DIM:
             if(gs.constraints == 1 && gs.n == 0) {
-                Constraint *c = SS.GetConstraint(gs.constraint[0]);
+                Constraint *c = SK.GetConstraint(gs.constraint[0]);
                 if(c->HasLabel() && !c->reference) {
                     SS.TW.shown.dimFinish = c->valA;
                     SS.TW.shown.dimSteps = 10;
@@ -416,7 +417,7 @@ void SolveSpace::MenuAnalyze(int id) {
         case GraphicsWindow::MNU_NAKED_EDGES: {
             SS.nakedEdges.Clear();
 
-            SMesh *m = &(SS.GetGroup(SS.GW.activeGroup)->runningMesh);
+            SMesh *m = &(SK.GetGroup(SS.GW.activeGroup)->runningMesh);
             SKdNode *root = SKdNode::From(m);
             bool inters, leaks;
             root->MakeNakedEdgesInto(&(SS.nakedEdges), &inters, &leaks);
@@ -440,7 +441,7 @@ void SolveSpace::MenuAnalyze(int id) {
         }
 
         case GraphicsWindow::MNU_VOLUME: {
-            SMesh *m = &(SS.GetGroup(SS.GW.activeGroup)->runningMesh);
+            SMesh *m = &(SK.GetGroup(SS.GW.activeGroup)->runningMesh);
            
             double vol = 0;
             int i;
diff --git a/solvespace.h b/solvespace.h
index af72bad5..abbb1ba8 100644
--- a/solvespace.h
+++ b/solvespace.h
@@ -410,26 +410,29 @@ public:
     void FinishAndCloseFile(void);
 };
 
-class SolveSpace {
+class Sketch {
 public:
-    TextWindow                  TW;
-    GraphicsWindow              GW;
-
-    // These lists define the sketch, and are edited by the user.
+    // These are user-editable, and define the sketch.
     IdList<Group,hGroup>            group;
-    IdList<Request,hRequest>        request;
     IdList<Constraint,hConstraint>  constraint;
+    IdList<Request,hRequest>        request;
 
-    // These lists are generated automatically when we solve the sketch.
+    // These are generated from the above.
     IdList<Entity,hEntity>          entity;
     IdList<Param,hParam>            param;
 
     inline Constraint *GetConstraint(hConstraint h)
         { return constraint.FindById(h); }
-    inline Request *GetRequest(hRequest h) { return request.FindById(h); }
     inline Entity  *GetEntity (hEntity  h) { return entity. FindById(h); }
     inline Param   *GetParam  (hParam   h) { return param.  FindById(h); }
+    inline Request *GetRequest(hRequest h) { return request.FindById(h); }
     inline Group   *GetGroup  (hGroup   h) { return group.  FindById(h); }
+};
+
+class SolveSpace {
+public:
+    TextWindow                  TW;
+    GraphicsWindow              GW;
 
     // The state for undo/redo
     typedef struct {
@@ -608,5 +611,6 @@ public:
 };
 
 extern SolveSpace SS;
+extern Sketch SK;
 
 #endif
diff --git a/system.cpp b/system.cpp
index d026abf9..7758cb08 100644
--- a/system.cpp
+++ b/system.cpp
@@ -21,7 +21,7 @@ void System::WriteJacobian(int tag) {
         if(e->tag != tag) continue;
 
         mat.eq[i] = e->h;
-        Expr *f = e->e->DeepCopyWithParamsAsPointers(&param, &(SS.param));
+        Expr *f = e->e->DeepCopyWithParamsAsPointers(&param, &(SK.param));
         f = f->FoldConstants();
 
         // Hash table (61 bits) to accelerate generation of zero partials.
@@ -33,7 +33,7 @@ void System::WriteJacobian(int tag) {
             {
                 pd = f->PartialWrt(mat.param[j]);
                 pd = pd->FoldConstants();
-                pd = pd->DeepCopyWithParamsAsPointers(&param, &(SS.param));
+                pd = pd->DeepCopyWithParamsAsPointers(&param, &(SK.param));
             } else {
                 pd = Expr::From(0.0);
             }
@@ -59,7 +59,7 @@ bool System::IsDragged(hParam p) {
         // The pending point could be one in a group that has not yet
         // been processed, in which case the lookup will fail; but
         // that's not an error.
-        Entity *pt = SS.entity.FindByIdNoOops(SS.GW.pending.point);
+        Entity *pt = SK.entity.FindByIdNoOops(SS.GW.pending.point);
         if(pt) {
             switch(pt->type) {
                 case Entity::POINT_N_TRANS:
@@ -77,9 +77,9 @@ bool System::IsDragged(hParam p) {
         }
     }
     if(SS.GW.pending.circle.v) {
-        Entity *circ = SS.entity.FindByIdNoOops(SS.GW.pending.circle);
+        Entity *circ = SK.entity.FindByIdNoOops(SS.GW.pending.circle);
         if(circ) {
-            Entity *dist = SS.GetEntity(circ->distance);
+            Entity *dist = SK.GetEntity(circ->distance);
             switch(dist->type) {
                 case Entity::DISTANCE:
                     if(p.v == (dist->param[0].v)) return true;
@@ -88,7 +88,7 @@ bool System::IsDragged(hParam p) {
         }
     }
     if(SS.GW.pending.normal.v) {
-        Entity *norm = SS.entity.FindByIdNoOops(SS.GW.pending.normal);
+        Entity *norm = SK.entity.FindByIdNoOops(SS.GW.pending.normal);
         if(norm) {
             switch(norm->type) {
                 case Entity::NORMAL_IN_3D:
@@ -343,22 +343,22 @@ bool System::NewtonSolve(int tag) {
 void System::WriteEquationsExceptFor(hConstraint hc, hGroup hg) {
     int i;
     // Generate all the equations from constraints in this group
-    for(i = 0; i < SS.constraint.n; i++) {
-        Constraint *c = &(SS.constraint.elem[i]);
+    for(i = 0; i < SK.constraint.n; i++) {
+        Constraint *c = &(SK.constraint.elem[i]);
         if(c->group.v != hg.v) continue;
         if(c->h.v == hc.v) continue;
 
         c->Generate(&eq);
     }
     // And the equations from entities
-    for(i = 0; i < SS.entity.n; i++) {
-        Entity *e = &(SS.entity.elem[i]);
+    for(i = 0; i < SK.entity.n; i++) {
+        Entity *e = &(SK.entity.elem[i]);
         if(e->group.v != hg.v) continue;
 
         e->GenerateEquations(&eq);
     }
     // And from the groups themselves
-    (SS.GetGroup(hg))->GenerateEquations(&eq);
+    (SK.GetGroup(hg))->GenerateEquations(&eq);
 }
 
 void System::FindWhichToRemoveToFixJacobian(Group *g) {
@@ -366,8 +366,8 @@ void System::FindWhichToRemoveToFixJacobian(Group *g) {
     (g->solved.remove).Clear();
 
     for(a = 0; a < 2; a++) {
-        for(i = 0; i < SS.constraint.n; i++) {
-            Constraint *c = &(SS.constraint.elem[i]);
+        for(i = 0; i < SK.constraint.n; i++) {
+            Constraint *c = &(SK.constraint.elem[i]);
             if(c->group.v != g->h.v) continue;
             if((c->type == Constraint::POINTS_COINCIDENT && a == 0) ||
                (c->type != Constraint::POINTS_COINCIDENT && a == 1))
@@ -502,7 +502,7 @@ void System::Solve(Group *g, bool andFindFree) {
         } else {
             val = p->val;
         }
-        Param *pp = SS.GetParam(p->h);
+        Param *pp = SK.GetParam(p->h);
         pp->val = val;
         pp->known = true;
         pp->free = p->free;
@@ -516,14 +516,14 @@ void System::Solve(Group *g, bool andFindFree) {
 didnt_converge:
     g->solved.how = Group::DIDNT_CONVERGE;
     (g->solved.remove).Clear();
-    SS.constraint.ClearTags();
+    SK.constraint.ClearTags();
     for(i = 0; i < eq.n; i++) {
         if(fabs(mat.B.num[i]) > CONVERGE_TOLERANCE || isnan(mat.B.num[i])) {
             // This constraint is unsatisfied.
             if(!mat.eq[i].isFromConstraint()) continue;
 
             hConstraint hc = mat.eq[i].constraint();
-            Constraint *c = SS.constraint.FindByIdNoOops(hc);
+            Constraint *c = SK.constraint.FindByIdNoOops(hc);
             if(!c) continue;
             // Don't double-show constraints that generated multiple
             // unsatisfied equations
diff --git a/textscreens.cpp b/textscreens.cpp
index 2e8ccb31..20764ec3 100644
--- a/textscreens.cpp
+++ b/textscreens.cpp
@@ -11,7 +11,7 @@ void TextWindow::ShowHeader(bool withNav) {
     ClearScreen();
 
     char *cd = SS.GW.LockedInWorkplane() ?
-                   SS.GetEntity(SS.GW.ActiveWorkplane())->DescriptionString() :
+                   SK.GetEntity(SS.GW.ActiveWorkplane())->DescriptionString() :
                    "free in 3d";
 
     // Navigation buttons
@@ -58,7 +58,7 @@ void TextWindow::ScreenSelectGroup(int link, DWORD v) {
 }
 void TextWindow::ScreenToggleGroupShown(int link, DWORD v) {
     hGroup hg = { v };
-    Group *g = SS.GetGroup(hg);
+    Group *g = SK.GetGroup(hg);
     g->visible = !(g->visible);
     // If a group was just shown, then it might not have been generated
     // previously, so regenerate.
@@ -66,8 +66,8 @@ void TextWindow::ScreenToggleGroupShown(int link, DWORD v) {
 }
 void TextWindow::ScreenShowGroupsSpecial(int link, DWORD v) {
     int i;
-    for(i = 0; i < SS.group.n; i++) {
-        Group *g = &(SS.group.elem[i]);
+    for(i = 0; i < SK.group.n; i++) {
+        Group *g = &(SK.group.elem[i]);
 
         if(link == 's') {
             g->visible = true;
@@ -78,10 +78,10 @@ void TextWindow::ScreenShowGroupsSpecial(int link, DWORD v) {
 }
 void TextWindow::ScreenActivateGroup(int link, DWORD v) {
     hGroup hg = { v };
-    Group *g = SS.GetGroup(hg);
+    Group *g = SK.GetGroup(hg);
     g->visible = true;
     SS.GW.activeGroup.v = v;
-    SS.GetGroup(SS.GW.activeGroup)->Activate();
+    SK.GetGroup(SS.GW.activeGroup)->Activate();
     SS.GW.ClearSuper();
 }
 void TextWindow::ReportHowGroupSolved(hGroup hg) {
@@ -107,8 +107,8 @@ void TextWindow::ShowListOfGroups(void) {
     Printf(true, "%Ftactv  show  ok  group-name%E");
     int i;
     bool afterActive = false;
-    for(i = 0; i < SS.group.n; i++) {
-        Group *g = &(SS.group.elem[i]);
+    for(i = 0; i < SK.group.n; i++) {
+        Group *g = &(SK.group.elem[i]);
         char *s = g->DescriptionString();
         bool active = (g->h.v == SS.GW.activeGroup.v);
         bool shown = g->visible;
@@ -172,7 +172,7 @@ void TextWindow::ScreenHoverConstraint(int link, DWORD v) {
     if(!SS.GW.showConstraints) return;
 
     hConstraint hc = { v };
-    Constraint *c = SS.GetConstraint(hc);
+    Constraint *c = SK.GetConstraint(hc);
     if(c->group.v != SS.GW.activeGroup.v) {
         // Only constraints in the active group are visible
         return;
@@ -199,7 +199,7 @@ void TextWindow::ScreenSelectRequest(int link, DWORD v) {
 void TextWindow::ScreenChangeOneOrTwoSides(int link, DWORD v) {
     SS.UndoRemember();
 
-    Group *g = SS.GetGroup(SS.TW.shown.group);
+    Group *g = SK.GetGroup(SS.TW.shown.group);
     if(g->subtype == Group::ONE_SIDED) {
         g->subtype = Group::TWO_SIDED;
     } else if(g->subtype == Group::TWO_SIDED) {
@@ -212,7 +212,7 @@ void TextWindow::ScreenChangeOneOrTwoSides(int link, DWORD v) {
 void TextWindow::ScreenChangeSkipFirst(int link, DWORD v) {
     SS.UndoRemember();
 
-    Group *g = SS.GetGroup(SS.TW.shown.group);
+    Group *g = SK.GetGroup(SS.TW.shown.group);
     (g->skipFirst) = !(g->skipFirst);
     SS.MarkGroupDirty(g->h);
     SS.GenerateAll();
@@ -221,7 +221,7 @@ void TextWindow::ScreenChangeSkipFirst(int link, DWORD v) {
 void TextWindow::ScreenChangeMeshCombine(int link, DWORD v) {
     SS.UndoRemember();
 
-    Group *g = SS.GetGroup(SS.TW.shown.group);
+    Group *g = SK.GetGroup(SS.TW.shown.group);
     g->meshCombine = v;
     SS.MarkGroupDirty(g->h);
     SS.GenerateAll();
@@ -230,7 +230,7 @@ void TextWindow::ScreenChangeMeshCombine(int link, DWORD v) {
 void TextWindow::ScreenChangeSuppress(int link, DWORD v) {
     SS.UndoRemember();
 
-    Group *g = SS.GetGroup(SS.TW.shown.group);
+    Group *g = SK.GetGroup(SS.TW.shown.group);
     g->suppress = !(g->suppress);
     SS.MarkGroupDirty(g->h);
     SS.GenerateAll();
@@ -239,7 +239,7 @@ void TextWindow::ScreenChangeSuppress(int link, DWORD v) {
 void TextWindow::ScreenChangeRightLeftHanded(int link, DWORD v) {
     SS.UndoRemember();
 
-    Group *g = SS.GetGroup(SS.TW.shown.group);
+    Group *g = SK.GetGroup(SS.TW.shown.group);
     if(g->subtype == Group::RIGHT_HANDED) {
         g->subtype = Group::LEFT_HANDED;
     } else {
@@ -250,7 +250,7 @@ void TextWindow::ScreenChangeRightLeftHanded(int link, DWORD v) {
     SS.GW.ClearSuper();
 }
 void TextWindow::ScreenChangeHelixParameter(int link, DWORD v) {
-    Group *g = SS.GetGroup(SS.TW.shown.group);
+    Group *g = SK.GetGroup(SS.TW.shown.group);
     char str[1024];
     int r;
     if(link == 't') {
@@ -272,7 +272,7 @@ void TextWindow::ScreenChangeHelixParameter(int link, DWORD v) {
 void TextWindow::ScreenColor(int link, DWORD v) {
     SS.UndoRemember();
 
-    Group *g = SS.GetGroup(SS.TW.shown.group);
+    Group *g = SK.GetGroup(SS.TW.shown.group);
     if(v < 0 || v >= SS.MODEL_COLORS) return;
     g->color = SS.modelColor[v];
     SS.MarkGroupDirty(g->h);
@@ -280,7 +280,7 @@ void TextWindow::ScreenColor(int link, DWORD v) {
     SS.GW.ClearSuper();
 }
 void TextWindow::ScreenChangeExprA(int link, DWORD v) {
-    Group *g = SS.GetGroup(SS.TW.shown.group);
+    Group *g = SK.GetGroup(SS.TW.shown.group);
 
     // There's an extra line for the skipFirst parameter in one-sided groups.
     int r = (g->subtype == Group::ONE_SIDED) ? 15 : 13;
@@ -292,7 +292,7 @@ void TextWindow::ScreenChangeExprA(int link, DWORD v) {
     SS.TW.edit.group.v = v;
 }
 void TextWindow::ScreenChangeGroupName(int link, DWORD v) {
-    Group *g = SS.GetGroup(SS.TW.shown.group);
+    Group *g = SK.GetGroup(SS.TW.shown.group);
     ShowTextEditControl(7, 14, g->DescriptionString()+5);
     SS.TW.edit.meaning = EDIT_GROUP_NAME;
     SS.TW.edit.group.v = v;
@@ -306,14 +306,14 @@ void TextWindow::ScreenDeleteGroup(int link, DWORD v) {
               "before proceeding.");
         return;
     }
-    SS.group.RemoveById(SS.TW.shown.group);
+    SK.group.RemoveById(SS.TW.shown.group);
     // This is a major change, so let's re-solve everything.
     SS.TW.ClearSuper();
     SS.GW.ClearSuper();
     SS.GenerateAll(0, INT_MAX);
 }
 void TextWindow::ShowGroupInfo(void) {
-    Group *g = SS.group.FindById(shown.group);
+    Group *g = SK.group.FindById(shown.group);
     char *s, *s2, *s3;
 
     if(shown.group.v == Group::HGROUP_REFERENCES.v) {
@@ -459,8 +459,8 @@ void TextWindow::ShowGroupInfo(void) {
     }
 
     int i, a = 0;
-    for(i = 0; i < SS.request.n; i++) {
-        Request *r = &(SS.request.elem[i]);
+    for(i = 0; i < SK.request.n; i++) {
+        Request *r = &(SK.request.elem[i]);
 
         if(r->group.v == shown.group.v) {
             char *s = r->DescriptionString();
@@ -475,8 +475,8 @@ void TextWindow::ShowGroupInfo(void) {
 
     a = 0;
     Printf(true, "%Ftconstraints in group (%d DOF)", g->solved.dof);
-    for(i = 0; i < SS.constraint.n; i++) {
-        Constraint *c = &(SS.constraint.elem[i]);
+    for(i = 0; i < SK.constraint.n; i++) {
+        Constraint *c = &(SK.constraint.elem[i]);
 
         if(c->group.v == shown.group.v) {
             char *s = c->DescriptionString();
@@ -497,7 +497,7 @@ void TextWindow::ShowGroupInfo(void) {
 // constraints that could be removed to fix it.
 //-----------------------------------------------------------------------------
 void TextWindow::ShowGroupSolveInfo(void) {
-    Group *g = SS.group.FindById(shown.group);
+    Group *g = SK.group.FindById(shown.group);
     if(g->solved.how == Group::SOLVED_OKAY) {
         // Go back to the default group info screen
         shown.screen = SCREEN_GROUP_INFO;
@@ -520,7 +520,7 @@ void TextWindow::ShowGroupSolveInfo(void) {
 
     for(int i = 0; i < g->solved.remove.n; i++) {
         hConstraint hc = g->solved.remove.elem[i];
-        Constraint *c = SS.constraint.FindByIdNoOops(hc);
+        Constraint *c = SK.constraint.FindByIdNoOops(hc);
         if(!c) continue;
 
         Printf(false, "%Bp   %Fl%Ll%D%f%h%s%E",
@@ -650,7 +650,7 @@ void TextWindow::ShowConfiguration(void) {
     Printf(false, "%Ba   %2 %Fl%Ll%f%D[change]%E; now %d triangles",
         SS.chordTol,
         &ScreenChangeChordTolerance, 0,
-        SS.GetGroup(SS.GW.activeGroup)->runningMesh.l.n);
+        SK.GetGroup(SS.GW.activeGroup)->runningMesh.l.n);
     Printf(false, "%Ft max piecewise linear segments%E");
     Printf(false, "%Ba    %d %Fl%Ll%f[change]%E",
         SS.maxSegments,
@@ -732,13 +732,13 @@ void TextWindow::ScreenStepDimSteps(int link, DWORD v) {
 }
 void TextWindow::ScreenStepDimGo(int link, DWORD v) {
     hConstraint hc = SS.TW.shown.constraint;
-    Constraint *c = SS.constraint.FindByIdNoOops(hc);
+    Constraint *c = SK.constraint.FindByIdNoOops(hc);
     if(c) {
         SS.UndoRemember();
         double start = c->valA, finish = SS.TW.shown.dimFinish;
         int i, n = SS.TW.shown.dimSteps;
         for(i = 1; i <= n; i++) {
-            c = SS.GetConstraint(hc);
+            c = SK.GetConstraint(hc);
             c->valA = start + ((finish - start)*i)/n;
             SS.MarkGroupDirty(c->group);
             SS.GenerateAll();
@@ -753,7 +753,7 @@ void TextWindow::ScreenStepDimGo(int link, DWORD v) {
     SS.TW.GoToScreen(SCREEN_LIST_OF_GROUPS);
 }
 void TextWindow::ShowStepDimension(void) {
-    Constraint *c = SS.constraint.FindByIdNoOops(shown.constraint);
+    Constraint *c = SK.constraint.FindByIdNoOops(shown.constraint);
     if(!c) {
         shown.screen = SCREEN_LIST_OF_GROUPS;
         Show();
@@ -812,13 +812,13 @@ void TextWindow::EditControlDone(char *s) {
                     break;
                 }
 
-                Group *g = SS.GetGroup(edit.group);
+                Group *g = SK.GetGroup(edit.group);
                 g->valA = ev;
 
                 if(g->type == Group::ROTATE) {
                     int i, c = 0;
-                    for(i = 0; i < SS.constraint.n; i++) {
-                        if(SS.constraint.elem[i].group.v == g->h.v) c++;
+                    for(i = 0; i < SK.constraint.n; i++) {
+                        if(SK.constraint.elem[i].group.v == g->h.v) c++;
                     }
                     // If the group does not contain any constraints, then
                     // set the numerical guess to space the copies uniformly
@@ -826,7 +826,7 @@ void TextWindow::EditControlDone(char *s) {
                     // already constrained, because that would break
                     // convergence.
                     if(c == 0) {
-                        SS.GetParam(g->h.param(3))->val = PI/(2*ev);
+                        SK.GetParam(g->h.param(3))->val = PI/(2*ev);
                     }
                 }
 
@@ -850,7 +850,7 @@ void TextWindow::EditControlDone(char *s) {
             } else {
                 SS.UndoRemember();
 
-                Group *g = SS.GetGroup(edit.group);
+                Group *g = SK.GetGroup(edit.group);
                 g->name.strcpy(s);
             }
             SS.unsaved = true;
@@ -936,7 +936,7 @@ void TextWindow::EditControlDone(char *s) {
         case EDIT_HELIX_PITCH:
         case EDIT_HELIX_DRADIUS: {
             SS.UndoRemember();
-            Group *g = SS.GetGroup(edit.group);
+            Group *g = SK.GetGroup(edit.group);
             Expr *e = Expr::From(s);
             if(!e) {
                 Error("Not a valid number or expression: '%s'", s);
@@ -955,7 +955,7 @@ void TextWindow::EditControlDone(char *s) {
         }
         case EDIT_TTF_TEXT: {
             SS.UndoRemember();
-            Request *r = SS.request.FindByIdNoOops(edit.request);
+            Request *r = SK.request.FindByIdNoOops(edit.request);
             if(r) {
                 r->str.strcpy(s);
                 SS.MarkGroupDirty(r->group);
diff --git a/textwin.cpp b/textwin.cpp
index 0b8cec0f..282998ed 100644
--- a/textwin.cpp
+++ b/textwin.cpp
@@ -236,7 +236,7 @@ void TextWindow::ScreenUnselectAll(int link, DWORD v) {
 
 void TextWindow::ScreenEditTtfText(int link, DWORD v) {
     hRequest hr = { v };
-    Request *r = SS.GetRequest(hr);
+    Request *r = SK.GetRequest(hr);
 
     ShowTextEditControl(13, 10, r->str.str);
     SS.TW.edit.meaning = EDIT_TTF_TEXT;
@@ -251,10 +251,10 @@ void TextWindow::ScreenSetTtfFont(int link, DWORD v) {
     SS.GW.GroupSelection();
     if(gs.entities != 1 || gs.n != 1) return;
 
-    Entity *e = SS.entity.FindByIdNoOops(gs.entity[0]);
+    Entity *e = SK.entity.FindByIdNoOops(gs.entity[0]);
     if(!e || e->type != Entity::TTF_TEXT || !e->h.isFromRequest()) return;
 
-    Request *r = SS.request.FindByIdNoOops(e->h.request());
+    Request *r = SK.request.FindByIdNoOops(e->h.request());
     if(!r) return;
    
     SS.UndoRemember();
@@ -271,7 +271,7 @@ void TextWindow::DescribeSelection(void) {
     Printf(false, "");
 
     if(gs.n == 1 && (gs.points == 1 || gs.entities == 1)) {
-        e = SS.GetEntity(gs.points == 1 ? gs.point[0] : gs.entity[0]);
+        e = SK.GetEntity(gs.points == 1 ? gs.point[0] : gs.entity[0]);
 
 #define COSTR(p) \
     SS.MmToString((p).x), SS.MmToString((p).y), SS.MmToString((p).z)
@@ -304,7 +304,7 @@ void TextWindow::DescribeSelection(void) {
                 break;
             }
             case Entity::WORKPLANE: {
-                p = SS.GetEntity(e->point[0])->PointGetNum();
+                p = SK.GetEntity(e->point[0])->PointGetNum();
                 Printf(false, "%FtWORKPLANE%E");
                 Printf(true, "   origin = " PT_AS_STR, COSTR(p));
                 Quaternion q = e->Normal()->NormalGetNum();
@@ -313,11 +313,11 @@ void TextWindow::DescribeSelection(void) {
                 break;
             }
             case Entity::LINE_SEGMENT: {
-                Vector p0 = SS.GetEntity(e->point[0])->PointGetNum();
+                Vector p0 = SK.GetEntity(e->point[0])->PointGetNum();
                 p = p0;
                 Printf(false, "%FtLINE SEGMENT%E");
                 Printf(true,  "   thru " PT_AS_STR, COSTR(p));
-                Vector p1 = SS.GetEntity(e->point[1])->PointGetNum();
+                Vector p1 = SK.GetEntity(e->point[1])->PointGetNum();
                 p = p1;
                 Printf(false, "        " PT_AS_STR, COSTR(p));
                 Printf(true,  "   len = %Fi%s%E",
@@ -327,18 +327,18 @@ void TextWindow::DescribeSelection(void) {
             case Entity::CUBIC:
                 Printf(false, "%FtCUBIC BEZIER CURVE%E");
                 for(i = 0; i <= 3; i++) {
-                    p = SS.GetEntity(e->point[i])->PointGetNum();
+                    p = SK.GetEntity(e->point[i])->PointGetNum();
                     Printf((i==0), "   p%c = " PT_AS_STR, '0'+i, COSTR(p));
                 }
                 break;
 
             case Entity::ARC_OF_CIRCLE: {
                 Printf(false, "%FtARC OF A CIRCLE%E");
-                p = SS.GetEntity(e->point[0])->PointGetNum();
+                p = SK.GetEntity(e->point[0])->PointGetNum();
                 Printf(true,  "     center = " PT_AS_STR, COSTR(p));
-                p = SS.GetEntity(e->point[1])->PointGetNum();
+                p = SK.GetEntity(e->point[1])->PointGetNum();
                 Printf(true,  "  endpoints = " PT_AS_STR, COSTR(p));
-                p = SS.GetEntity(e->point[2])->PointGetNum();
+                p = SK.GetEntity(e->point[2])->PointGetNum();
                 Printf(false, "              " PT_AS_STR, COSTR(p));
                 double r = e->CircleGetRadiusNum();
                 Printf(true, "   diameter =  %Fi%s", SS.MmToString(r*2));
@@ -350,7 +350,7 @@ void TextWindow::DescribeSelection(void) {
             }
             case Entity::CIRCLE: {
                 Printf(false, "%FtCIRCLE%E");
-                p = SS.GetEntity(e->point[0])->PointGetNum();
+                p = SK.GetEntity(e->point[0])->PointGetNum();
                 Printf(true,  "     center = " PT_AS_STR, COSTR(p));
                 double r = e->CircleGetRadiusNum();
                 Printf(true,  "   diameter =  %Fi%s", SS.MmToString(r*2));
@@ -403,40 +403,40 @@ void TextWindow::DescribeSelection(void) {
                 break;
         }
 
-        Group *g = SS.GetGroup(e->group);
+        Group *g = SK.GetGroup(e->group);
         Printf(false, "");
         Printf(false, "%FtIN GROUP%E      %s", g->DescriptionString());
         if(e->workplane.v == Entity::FREE_IN_3D.v) {
             Printf(false, "%FtNOT LOCKED IN WORKPLANE%E"); 
         } else {
-            Entity *w = SS.GetEntity(e->workplane);
+            Entity *w = SK.GetEntity(e->workplane);
             Printf(false, "%FtIN WORKPLANE%E  %s", w->DescriptionString());
         }
     } else if(gs.n == 2 && gs.points == 2) {
         Printf(false, "%FtTWO POINTS");
-        Vector p0 = SS.GetEntity(gs.point[0])->PointGetNum();
+        Vector p0 = SK.GetEntity(gs.point[0])->PointGetNum();
         Printf(true,  "   at " PT_AS_STR, COSTR(p0));
-        Vector p1 = SS.GetEntity(gs.point[1])->PointGetNum();
+        Vector p1 = SK.GetEntity(gs.point[1])->PointGetNum();
         Printf(false, "      " PT_AS_STR, COSTR(p1));
         double d = (p1.Minus(p0)).Magnitude();
         Printf(true, "  d = %Fi%s", SS.MmToString(d));
     } else if(gs.n == 2 && gs.faces == 1 && gs.points == 1) {
         Printf(false, "%FtA POINT AND A PLANE FACE");
-        Vector pt = SS.GetEntity(gs.point[0])->PointGetNum();
+        Vector pt = SK.GetEntity(gs.point[0])->PointGetNum();
         Printf(true,  "        point = " PT_AS_STR, COSTR(pt));
-        Vector n = SS.GetEntity(gs.face[0])->FaceGetNormalNum();
+        Vector n = SK.GetEntity(gs.face[0])->FaceGetNormalNum();
         Printf(true,  " plane normal = " PT_AS_NUM, CO(n));
-        Vector pl = SS.GetEntity(gs.face[0])->FaceGetPointNum();
+        Vector pl = SK.GetEntity(gs.face[0])->FaceGetPointNum();
         Printf(false, "   plane thru = " PT_AS_STR, COSTR(pl));
         double dd = n.Dot(pl) - n.Dot(pt);
         Printf(true,  "     distance = %Fi%s", SS.MmToString(dd));
     } else if(gs.n == 3 && gs.points == 2 && gs.vectors == 1) {
         Printf(false, "%FtTWO POINTS AND A VECTOR");
-        Vector p0 = SS.GetEntity(gs.point[0])->PointGetNum();
+        Vector p0 = SK.GetEntity(gs.point[0])->PointGetNum();
         Printf(true,  "  pointA = " PT_AS_STR, COSTR(p0));
-        Vector p1 = SS.GetEntity(gs.point[1])->PointGetNum();
+        Vector p1 = SK.GetEntity(gs.point[1])->PointGetNum();
         Printf(false, "  pointB = " PT_AS_STR, COSTR(p1));
-        Vector v  = SS.GetEntity(gs.vector[0])->VectorGetNum();
+        Vector v  = SK.GetEntity(gs.vector[0])->VectorGetNum();
         v = v.WithMagnitude(1);
         Printf(true,  "  vector = " PT_AS_NUM, CO(v));
         double d = (p1.Minus(p0)).Dot(v);
@@ -444,14 +444,14 @@ void TextWindow::DescribeSelection(void) {
     } else if(gs.n == 2 && gs.faces == 2) {
         Printf(false, "%FtTWO PLANE FACES");
 
-        Vector n0 = SS.GetEntity(gs.face[0])->FaceGetNormalNum();
+        Vector n0 = SK.GetEntity(gs.face[0])->FaceGetNormalNum();
         Printf(true,  " planeA normal = " PT_AS_NUM, CO(n0));
-        Vector p0 = SS.GetEntity(gs.face[0])->FaceGetPointNum();
+        Vector p0 = SK.GetEntity(gs.face[0])->FaceGetPointNum();
         Printf(false, "   planeA thru = " PT_AS_STR, COSTR(p0));
 
-        Vector n1 = SS.GetEntity(gs.face[1])->FaceGetNormalNum();
+        Vector n1 = SK.GetEntity(gs.face[1])->FaceGetNormalNum();
         Printf(true,  " planeB normal = " PT_AS_NUM, CO(n1));
-        Vector p1 = SS.GetEntity(gs.face[1])->FaceGetPointNum();
+        Vector p1 = SK.GetEntity(gs.face[1])->FaceGetPointNum();
         Printf(false, "   planeB thru = " PT_AS_STR, COSTR(p1));
 
         double theta = acos(n0.Dot(n1));
diff --git a/undoredo.cpp b/undoredo.cpp
index 0b3b5365..37794721 100644
--- a/undoredo.cpp
+++ b/undoredo.cpp
@@ -40,8 +40,8 @@ void SolveSpace::PushFromCurrentOnto(UndoStack *uk) {
 
     UndoState *ut = &(uk->d[uk->write]);
     ZERO(ut);
-    for(i = 0; i < group.n; i++) {
-        Group *src = &(group.elem[i]);
+    for(i = 0; i < SK.group.n; i++) {
+        Group *src = &(SK.group.elem[i]);
         Group dest = *src;
         // And then clean up all the stuff that needs to be a deep copy,
         // and zero out all the dynamic stuff that will get regenerated.
@@ -62,17 +62,17 @@ void SolveSpace::PushFromCurrentOnto(UndoStack *uk) {
         ZERO(&(dest.impEntity));
         ut->group.Add(&dest);
     }
-    for(i = 0; i < request.n; i++) {
-        ut->request.Add(&(request.elem[i]));
+    for(i = 0; i < SK.request.n; i++) {
+        ut->request.Add(&(SK.request.elem[i]));
     }
-    for(i = 0; i < constraint.n; i++) {
-        Constraint *src = &(constraint.elem[i]);
+    for(i = 0; i < SK.constraint.n; i++) {
+        Constraint *src = &(SK.constraint.elem[i]);
         Constraint dest = *src;
         ZERO(&(dest.dogd));
         ut->constraint.Add(&dest);
     }
-    for(i = 0; i < param.n; i++) {
-        ut->param.Add(&(param.elem[i]));
+    for(i = 0; i < SK.param.n; i++) {
+        ut->param.Add(&(SK.param.elem[i]));
     }
     ut->activeGroup = SS.GW.activeGroup;
 
@@ -88,8 +88,8 @@ void SolveSpace::PopOntoCurrentFrom(UndoStack *uk) {
 
     int i;
     // Free everything in the main copy of the program before replacing it
-    for(i = 0; i < group.n; i++) {
-        Group *g = &(group.elem[i]);
+    for(i = 0; i < SK.group.n; i++) {
+        Group *g = &(SK.group.elem[i]);
         g->poly.Clear();
         g->bezierLoopSet.Clear();
         g->runningMesh.Clear();
@@ -100,16 +100,16 @@ void SolveSpace::PopOntoCurrentFrom(UndoStack *uk) {
         g->impMesh.Clear();
         g->impEntity.Clear();
     }
-    group.Clear();
-    request.Clear();
-    constraint.Clear();
-    param.Clear();
+    SK.group.Clear();
+    SK.request.Clear();
+    SK.constraint.Clear();
+    SK.param.Clear();
 
     // And then do a shallow copy of the state from the undo list
-    ut->group.MoveSelfInto(&group);
-    ut->request.MoveSelfInto(&request);
-    ut->constraint.MoveSelfInto(&constraint);
-    ut->param.MoveSelfInto(&param);
+    ut->group.MoveSelfInto(&(SK.group));
+    ut->request.MoveSelfInto(&(SK.request));
+    ut->constraint.MoveSelfInto(&(SK.constraint));
+    ut->param.MoveSelfInto(&(SK.param));
     SS.GW.activeGroup = ut->activeGroup;
 
     // No need to free it, since a shallow copy was made above
diff --git a/util.cpp b/util.cpp
index 94d3a1c1..e025b519 100644
--- a/util.cpp
+++ b/util.cpp
@@ -113,10 +113,10 @@ Quaternion Quaternion::From(double w, double vx, double vy, double vz) {
 
 Quaternion Quaternion::From(hParam w, hParam vx, hParam vy, hParam vz) {
     Quaternion q;
-    q.w  = SS.GetParam(w )->val;
-    q.vx = SS.GetParam(vx)->val;
-    q.vy = SS.GetParam(vy)->val;
-    q.vz = SS.GetParam(vz)->val;
+    q.w  = SK.GetParam(w )->val;
+    q.vx = SK.GetParam(vx)->val;
+    q.vy = SK.GetParam(vy)->val;
+    q.vz = SK.GetParam(vz)->val;
     return q;
 }
 
@@ -277,9 +277,9 @@ Vector Vector::From(double x, double y, double z) {
 
 Vector Vector::From(hParam x, hParam y, hParam z) {
     Vector v;
-    v.x = SS.GetParam(x)->val;
-    v.y = SS.GetParam(y)->val;
-    v.z = SS.GetParam(z)->val;
+    v.x = SK.GetParam(x)->val;
+    v.y = SK.GetParam(y)->val;
+    v.z = SK.GetParam(z)->val;
     return v;
 }
 
@@ -504,7 +504,7 @@ Vector Vector::WithMagnitude(double v) {
 }
 
 Vector Vector::ProjectVectorInto(hEntity wrkpl) {
-    Entity *w = SS.GetEntity(wrkpl);
+    Entity *w = SK.GetEntity(wrkpl);
     Vector u = w->Normal()->NormalU();
     Vector v = w->Normal()->NormalV();
 
@@ -515,7 +515,7 @@ Vector Vector::ProjectVectorInto(hEntity wrkpl) {
 }
 
 Vector Vector::ProjectInto(hEntity wrkpl) {
-    Entity *w = SS.GetEntity(wrkpl);
+    Entity *w = SK.GetEntity(wrkpl);
     Vector p0 = w->WorkplaneGetOffset();
 
     Vector f = this->Minus(p0);