diff --git a/draw.cpp b/draw.cpp
index 484a5bac..f73053d1 100644
--- a/draw.cpp
+++ b/draw.cpp
@@ -548,6 +548,11 @@ void GraphicsWindow::MouseLeftDoubleClick(double mx, double my) {
         ClearSuper();
 
         Constraint *c = SS.GetConstraint(constraintBeingEdited);
+        if(c->reference) {
+            // Not meaningful to edit a reference dimension
+            return;
+        }
+
         Vector p3 = c->GetLabelPos();
         Point2d p2 = ProjectPoint(p3);
         ShowGraphicsEditControl((int)p2.x, (int)p2.y, c->exprA->Print());
diff --git a/dsc.h b/dsc.h
index 50f0254a..92f97f2d 100644
--- a/dsc.h
+++ b/dsc.h
@@ -106,20 +106,26 @@ public:
             elem = (T *)MemRealloc(elem, elemsAllocated*sizeof(elem[0]));
         }
 
-        int i = 0;
-        if(n == 0 || elem[n-1].h.v < t->h.v) {
-            i = n;
-        } else {
-            while(i < n && elem[i].h.v < t->h.v) {
-                i++;
+        int first = 0, last = n;
+        // We know that we must insert within the closed interval [first,last]
+        while(first != last) {
+            int mid = (first + last)/2;
+            H hm = elem[mid].h;
+            if(hm.v > t->h.v) {
+                last = mid;
+            } else if(hm.v < t->h.v) {
+                first = mid + 1;
+            } else {
+                oops();
             }
         }
-        if(i < n && elem[i].h.v == t->h.v) oops();
+        int i = first;
+
         memmove(elem+i+1, elem+i, (n-i)*sizeof(elem[0]));
         elem[i] = *t;
         n++;
     }
-    
+
     T *FindById(H h) {
         T *t = FindByIdNoOops(h);
         if(!t) {
diff --git a/entity.cpp b/entity.cpp
index 057d27f2..ee6ab84c 100644
--- a/entity.cpp
+++ b/entity.cpp
@@ -680,6 +680,6 @@ void Entity::CalculateNumerical(void) {
         Vector n = FaceGetNormalNum();
         numNormal = Quaternion::From(0, n.x, n.y, n.z);
     }
-    visible = IsVisible();
+    actVisible = IsVisible();
 }
 
diff --git a/file.cpp b/file.cpp
index 7eb1f826..64cc6c17 100644
--- a/file.cpp
+++ b/file.cpp
@@ -68,6 +68,7 @@ const SolveSpace::SaveTable SolveSpace::SAVED[] = {
     { 'g',  "Group.exprA",              'E',    &(SS.sv.g.exprA)              },
     { 'g',  "Group.color",              'x',    &(SS.sv.g.color)              },
     { 'g',  "Group.subtype",            'd',    &(SS.sv.g.subtype)            },
+    { 'g',  "Group.skipFirst",          'b',    &(SS.sv.g.skipFirst)          },
     { 'g',  "Group.meshCombine",        'd',    &(SS.sv.g.meshCombine)        },
     { 'g',  "Group.predef.q.w",         'f',    &(SS.sv.g.predef.q.w)         },
     { 'g',  "Group.predef.q.vx",        'f',    &(SS.sv.g.predef.q.vx)        },
@@ -94,7 +95,6 @@ const SolveSpace::SaveTable SolveSpace::SAVED[] = {
 
     { 'e',  "Entity.h.v",               'x',    &(SS.sv.e.h.v)                },
     { 'e',  "Entity.type",              'd',    &(SS.sv.e.type)               },
-    { 'e',  "Entity.visible",           'b',    &(SS.sv.e.visible)            },
     { 'e',  "Entity.group.v",           'x',    &(SS.sv.e.group.v)            },
     { 'e',  "Entity.construction",      'b',    &(SS.sv.e.construction)       },
     { 'e',  "Entity.param[0].v",        'x',    &(SS.sv.e.param[0].v)         },
@@ -127,6 +127,7 @@ const SolveSpace::SaveTable SolveSpace::SAVED[] = {
     { 'e',  "Entity.actNormal.vy",      'f',    &(SS.sv.e.actNormal.vy)       },
     { 'e',  "Entity.actNormal.vz",      'f',    &(SS.sv.e.actNormal.vz)       },
     { 'e',  "Entity.actDistance",       'f',    &(SS.sv.e.actDistance)        },
+    { 'e',  "Entity.actVisible",        'b',    &(SS.sv.e.actVisible),        },
 
 
     { 'c',  "Constraint.h.v",           'x',    &(SS.sv.c.h.v)                },
diff --git a/group.cpp b/group.cpp
index b70fe34e..129bfeb8 100644
--- a/group.cpp
+++ b/group.cpp
@@ -130,6 +130,8 @@ void Group::MenuGroup(int id) {
             g.opA = SS.GW.activeGroup;
             g.exprA = Expr::From(3)->DeepCopyKeep();
             g.subtype = ONE_SIDED;
+            g.predef.entityB = SS.GW.ActiveWorkplane();
+            g.activeWorkplane = SS.GW.ActiveWorkplane();
             g.name.strcpy("translate");
             break;
 
@@ -294,8 +296,12 @@ void Group::Generate(IdList<Entity,hEntity> *entity,
             AddParam(param, h.param(1), gp.y);
             AddParam(param, h.param(2), gp.z);
 
-            int n = (int)(exprA->Eval());
-            for(a = 0; a < n; a++) {
+            int n = (int)(exprA->Eval()), a0 = 0;
+            if(subtype == ONE_SIDED && skipFirst) {
+                a0++; n++;
+            }
+
+            for(a = a0; a < n; a++) {
                 for(i = 0; i < entity->n; i++) {
                     Entity *e = &(entity->elem[i]);
                     if(e->group.v != opA.v) continue;
@@ -322,8 +328,12 @@ void Group::Generate(IdList<Entity,hEntity> *entity,
             AddParam(param, h.param(5), gn.y);
             AddParam(param, h.param(6), gn.z);
 
-            int n = (int)(exprA->Eval());
-            for(a = 0; a < n; a++) {
+            int n = (int)(exprA->Eval()), a0 = 0;
+            if(subtype == ONE_SIDED && skipFirst) {
+                a0++; n++;
+            }
+
+            for(a = a0; a < n; a++) {
                 for(i = 0; i < entity->n; i++) {
                     Entity *e = &(entity->elem[i]);
                     if(e->group.v != opA.v) continue;
@@ -352,7 +362,6 @@ void Group::Generate(IdList<Entity,hEntity> *entity,
             
             for(i = 0; i < impEntity.n; i++) {
                 Entity *ie = &(impEntity.elem[i]);
-
                 CopyEntity(entity, ie, 0, 0,
                     h.param(0), h.param(1), h.param(2),
                     h.param(3), h.param(4), h.param(5), h.param(6),
@@ -408,19 +417,39 @@ void Group::GenerateEquations(IdList<Equation,hEquation> *l) {
             AddEq(l, u.Dot(extruden), 0);
             AddEq(l, v.Dot(extruden), 1);
         }
+    } else if(type == TRANSLATE) {
+        if(predef.entityB.v != Entity::FREE_IN_3D.v) {
+            Entity *w = SS.GetEntity(predef.entityB);
+            ExprVector n = w->Normal()->NormalExprsN();
+            ExprVector trans;
+            trans = ExprVector::From(h.param(0), h.param(1), h.param(2));
+
+            // The translation vector is parallel to the workplane
+            AddEq(l, trans.Dot(n), 0);
+        }
     }
 }
 
 hEntity Group::Remap(hEntity in, int copyNumber) {
-    int i;
+    // A hash table is used to accelerate the search
+    int hash = ((unsigned)(in.v*61 + copyNumber)) % REMAP_PRIME;
+    int i = remapCache[hash];
+    if(i >= 0 && i < remap.n) {
+        EntityMap *em = &(remap.elem[i]);
+        if(em->input.v == in.v && em->copyNumber == copyNumber) {
+            return h.entity(em->h.v);
+        }
+    }
+    // but if we don't find it in the hash table, then linear search
     for(i = 0; i < remap.n; i++) {
         EntityMap *em = &(remap.elem[i]);
         if(em->input.v == in.v && em->copyNumber == copyNumber) {
             // We already have a mapping for this entity.
+            remapCache[hash] = i;
             return h.entity(em->h.v);
         }
     }
-    // We don't have a mapping yet, so create one.
+    // And if we still don't find it, then create a new entry.
     EntityMap em;
     em.input = in;
     em.copyNumber = copyNumber;
diff --git a/groupmesh.cpp b/groupmesh.cpp
index 02653bb4..51280858 100644
--- a/groupmesh.cpp
+++ b/groupmesh.cpp
@@ -18,11 +18,17 @@ void Group::GeneratePolygon(void) {
         }
         SEdge error;
         if(edges.AssemblePolygon(&poly, &error)) {
-            polyError.yes = false;
+            polyError.how = POLY_GOOD;
             poly.normal = poly.ComputeNormal();
             poly.FixContourDirections();
+
+            if(!poly.AllPointsInPlane(&(polyError.notCoplanarAt))) {
+                // The edges aren't all coplanar; so not a good polygon
+                polyError.how = POLY_NOT_COPLANAR;
+                poly.Clear();
+            }
         } else {
-            polyError.yes = true;
+            polyError.how = POLY_NOT_CLOSED;
             polyError.notClosedAt = error;
             poly.Clear();
         }
@@ -279,8 +285,10 @@ void Group::Draw(void) {
 
     if(SS.GW.showMesh) glxDebugMesh(&mesh);
 
+    // And finally show the polygons too
     if(!SS.GW.showShaded) return;
-    if(polyError.yes) {
+    if(polyError.how == POLY_NOT_CLOSED) {
+        glDisable(GL_DEPTH_TEST);
         glxColor4d(1, 0, 0, 0.2);
         glLineWidth(10);
         glBegin(GL_LINES);
@@ -294,6 +302,16 @@ void Group::Draw(void) {
             glxOntoWorkplane(SS.GW.projRight, SS.GW.projUp);
             glxWriteText("not closed contour!");
         glPopMatrix();
+        glEnable(GL_DEPTH_TEST);
+    } else if(polyError.how == POLY_NOT_COPLANAR) {
+        glDisable(GL_DEPTH_TEST);
+        glxColor3d(1, 0, 0);
+        glPushMatrix();
+            glxTranslatev(polyError.notCoplanarAt);
+            glxOntoWorkplane(SS.GW.projRight, SS.GW.projUp);
+            glxWriteText("points not all coplanar!");
+        glPopMatrix();
+        glEnable(GL_DEPTH_TEST);
     } else {
         glxColor4d(0, 0.1, 0.1, 0.5);
         glPolygonOffset(-1, -1);
diff --git a/polygon.cpp b/polygon.cpp
index 5f501a2b..3b61f9a3 100644
--- a/polygon.cpp
+++ b/polygon.cpp
@@ -179,6 +179,18 @@ bool SContour::ContainsPointProjdToNormal(Vector n, Vector p) {
     return inside;
 }
 
+bool SContour::AllPointsInPlane(Vector n, double d, Vector *notCoplanarAt) {
+    for(int i = 0; i < l.n; i++) {
+        Vector p = l.elem[i].p;
+        double dd = n.Dot(p) - d;
+        if(fabs(dd) > 10*LENGTH_EPS) {
+            *notCoplanarAt = p;
+            return false;
+        }
+    }
+    return true;
+}
+
 void SContour::Reverse(void) {
     int i;
     for(i = 0; i < (l.n / 2); i++) {
@@ -263,6 +275,20 @@ void SPolygon::FixContourDirections(void) {
     }
 }
 
+bool SPolygon::AllPointsInPlane(Vector *notCoplanarAt) {
+    if(l.n == 0 || l.elem[0].l.n == 0) return true;
+
+    Vector p0 = l.elem[0].l.elem[0].p;
+    double d = normal.Dot(p0);
+
+    for(int i = 0; i < l.n; i++) {
+        if(!(l.elem[i]).AllPointsInPlane(normal, d, notCoplanarAt)) {
+            return false;
+        }
+    }
+    return true;
+}
+
 static int TriMode, TriVertexCount;
 static Vector Tri1, TriNMinus1, TriNMinus2;
 static Vector TriNormal;
diff --git a/polygon.h b/polygon.h
index 96a5077a..281bf235 100644
--- a/polygon.h
+++ b/polygon.h
@@ -84,6 +84,7 @@ public:
     Vector ComputeNormal(void);
     bool IsClockwiseProjdToNormal(Vector n);
     bool ContainsPointProjdToNormal(Vector n, Vector p);
+    bool AllPointsInPlane(Vector n, double d, Vector *notCoplanarAt);
 };
 
 class SPolygon {
@@ -99,6 +100,7 @@ public:
     void FixContourDirections(void);
     void TriangulateInto(SMesh *m);
     void Clear(void);
+    bool AllPointsInPlane(Vector *notCoplanarAt);
 };
 
 typedef struct {
diff --git a/sketch.h b/sketch.h
index bfff8df9..d238913a 100644
--- a/sketch.h
+++ b/sketch.h
@@ -108,6 +108,8 @@ public:
     static const int TWO_SIDED                  = 7001;
     int subtype;
 
+    bool skipFirst; // for step and repeat ops
+
     struct {
         Quaternion  q;
         Vector      p;
@@ -120,10 +122,15 @@ public:
     } predef;
 
     SPolygon        poly;
+    static const int POLY_GOOD          = 0;
+    static const int POLY_NOT_CLOSED    = 1;
+    static const int POLY_NOT_COPLANAR  = 2;
     struct {
+        int             how;
         SEdge           notClosedAt;
-        bool            yes;
+        Vector          notCoplanarAt;
     }               polyError;
+
     SMesh           mesh;
     struct {
         SMesh           interferesAt;
@@ -136,6 +143,8 @@ public:
     int meshCombine;
 
     IdList<EntityMap,EntityId> remap;
+    static const int REMAP_PRIME = 19477;
+    int remapCache[REMAP_PRIME];
 
     char                       impFile[MAX_PATH];
     SMesh                      impMesh;
@@ -272,8 +281,6 @@ public:
     double      numDistance;
     // and a bit more state that the faces need
     Vector      numVector;
-    // and the shown state also gets saved here, for later import
-    bool        visible;
 
     // All points/normals/distances have their numerical value; this is
     // a convenience, to simplify the import/assembly code, so that the
@@ -281,6 +288,8 @@ public:
     Vector      actPoint;
     Quaternion  actNormal;
     double      actDistance;
+    // and the shown state also gets saved here, for later import
+    bool        actVisible;
 
     hGroup      group;
     hEntity     workplane;   // or Entity::FREE_IN_3D
diff --git a/textwin.cpp b/textwin.cpp
index 68977c0f..55fd1eaf 100644
--- a/textwin.cpp
+++ b/textwin.cpp
@@ -560,6 +560,15 @@ void TextWindow::ScreenChangeOneOrTwoSides(int link, DWORD v) {
     SS.GenerateAll();
     SS.GW.ClearSuper();
 }
+void TextWindow::ScreenChangeSkipFirst(int link, DWORD v) {
+    SS.UndoRemember();
+
+    Group *g = SS.GetGroup(SS.TW.shown->group);
+    (g->skipFirst) = !(g->skipFirst);
+    SS.MarkGroupDirty(g->h);
+    SS.GenerateAll();
+    SS.GW.ClearSuper();
+}
 void TextWindow::ScreenChangeMeshCombine(int link, DWORD v) {
     SS.UndoRemember();
 
@@ -581,7 +590,11 @@ void TextWindow::ScreenColor(int link, DWORD v) {
 }
 void TextWindow::ScreenChangeExprA(int link, DWORD v) {
     Group *g = SS.GetGroup(SS.TW.shown->group);
-    ShowTextEditControl(13, 10, g->exprA->Print());
+
+    // There's an extra line for the skipFirst parameter in one-sided groups.
+    int r = (g->subtype == Group::ONE_SIDED) ? 15 : 13;
+
+    ShowTextEditControl(r, 9, g->exprA->Print());
     SS.TW.edit.meaning = EDIT_TIMES_REPEATED;
     SS.TW.edit.group.v = v;
 }
@@ -608,7 +621,7 @@ void TextWindow::ScreenDeleteGroup(int link, DWORD v) {
 }
 void TextWindow::ShowGroupInfo(void) {
     Group *g = SS.group.FindById(shown->group);
-    char *s, *s2;
+    char *s, *s2, *s3;
 
     if(shown->group.v == Group::HGROUP_REFERENCES.v) {
         Printf(true, "%FtGROUP    %E%s", g->DescriptionString());
@@ -628,10 +641,12 @@ void TextWindow::ShowGroupInfo(void) {
         s = "EXTRUDE ";
     } else if(g->type == Group::TRANSLATE) {
         s = "TRANSLATE";
-        s2 ="REPEAT   ";
+        s2 ="REPEAT  ";
+        s3 ="START   ";
     } else if(g->type == Group::ROTATE) {
-        s = "ROTATE";
-        s2 ="REPEAT";
+        s = "ROTATE  ";
+        s2 ="REPEAT  ";
+        s3 ="START   ";
     }
 
     if(g->type == Group::EXTRUDE || g->type == Group::ROTATE ||
@@ -649,8 +664,22 @@ void TextWindow::ShowGroupInfo(void) {
     }
 
     if(g->type == Group::ROTATE || g->type == Group::TRANSLATE) {
+        bool space;
+        if(g->subtype == Group::ONE_SIDED) {
+            bool skip = g->skipFirst;
+            Printf(true, "%Ft%s%E %Fh%f%Ll%s%E%Fs%s%E / %Fh%f%Ll%s%E%Fs%s%E",
+                s3,
+                &ScreenChangeSkipFirst,
+                (!skip ? "" : "with original"), (!skip ? "with original" : ""),
+                &ScreenChangeSkipFirst,
+                (skip ? "":"with copy #1"), (skip ? "with copy #1":""));
+            space = false;
+        } else {
+            space = true;
+        }
+
         int times = (int)(g->exprA->Eval());
-        Printf(true, "%Ft%s%E %d time%s %Fl%Ll%D%f[change]%E",
+        Printf(space, "%Ft%s%E %d time%s %Fl%Ll%D%f[change]%E",
             s2, times, times == 1 ? "" : "s",
             g->h.v, &TextWindow::ScreenChangeExprA);
     }
@@ -695,7 +724,14 @@ void TextWindow::ShowGroupInfo(void) {
             0x80000000 | SS.modelColor[7], 7, &TextWindow::ScreenColor);
     }
 
-    Printf(true, "%Ftrequests in group");
+    // Leave more space if the group has configuration stuff above the req/
+    // constraint list (as all but the drawing groups do).
+    if(g->type == Group::DRAWING_3D || g->type == Group::DRAWING_WORKPLANE) {
+        Printf(true, "%Ftrequests in group");
+    } else {
+        Printf(false, "");
+        Printf(false, "%Ftrequests in group");
+    }
 
     int i, a = 0;
     for(i = 0; i < SS.request.n; i++) {
diff --git a/ui.h b/ui.h
index 5e345a03..a8962ea0 100644
--- a/ui.h
+++ b/ui.h
@@ -100,6 +100,7 @@ public:
     static void ScreenUnselectAll(int link, DWORD v);
 
     static void ScreenChangeOneOrTwoSides(int link, DWORD v);
+    static void ScreenChangeSkipFirst(int link, DWORD v);
     static void ScreenChangeMeshCombine(int link, DWORD v);
     static void ScreenColor(int link, DWORD v);
 
diff --git a/wishlist.txt b/wishlist.txt
index 72d48868..d65ffe87 100644
--- a/wishlist.txt
+++ b/wishlist.txt
@@ -1,15 +1,13 @@
 
 STL check for meshes, and T intersection removal
 STL export
-better triangle combining (Simplify()) for meshes
 DXF export
-compress file format (binary?)
 partitioned subsystems in the solver
 TTF font text
 display with proper formatting/units
 more measurements
 some kind of rounding / chamfer
-auto-constrain translate in then-active workplane
 remove back button in browser?
-
+clean up user-created workplanes
+incremental regen of entities?