12 KiB
Issues
There are limitations to what can be styled with stylesheets, as well as rare bugs that prevent certain styles or widgets from rendering properly. This is a list of known issues, as well as suitable workarounds. THese issues are organized by the widget type, then the description of the properties/styles they affect.
QCompleter
Menu Hover Background Color
QCompleter doesn't have a hover background color in Qt5 on the drop-down menu. This works fine in Qt6, and changing rules for QListView (the drop-down menu) changes the drop-down menu in Qt6, but not Qt5.
QDial
Custom Style
QDial cannot be customized via a stylesheet, which is a known bug in QTBUG-1160. An example of how to style a QDial is available in dial.py. This works out-of-the-box, and can be a drop-in replacement for QDial.
QSlider
Invisible Ticks
QSlider ticks disappear when using stylesheets, which is a known bug referenced in QTBUG-3304 and QTBUG-3564. An example of how to style a QSlider is available in slider.py, however, this does not work with a stylesheet applied to a QSlider.
QTabBar
Triangular Tab Color
The text and border colors of a triangular QTabBar must be the same. This cannot be modified via a stylesheet.
Triangular Tab Hover Background Color
Triangular tab bars do not have :hover pseudo-states for non-selected tabs. Only the selected tab has a :hover pseudo-state, defeating the purpose. This could be fixed by installing an event filter for a HoverEnter or HoverMove event.
Triangular Tab Padding
Custom padding for triangular QTabBars on the bottom is ignored. All other tab positions work.
QTextDocument
Placeholder Text
For the widgets QTextEdit, QPlainTextEdit, and QLineEdit, which use an internal QTextDocument, you can set placeholder text for when no text is present. In Qt5, this is correctly grayed out when the placeholder text is present, which is not respected in Qt6 (as of Qt version 6.3.0).
An example of a workaround placeholder_text.py, which only works currently for Qt5 or Qt6 without a stylesheet. Using the native stylesheet shows it uses hard-coded colors for Qt6, so this is almost certainly a Qt bug. This is likely referenced in QTBUG-92947 and QTCREATORBUG-25444.
An example workaround setting the placeholder text at palette at the application level (for all widgets) is as follows. You can also set the placeholder text color for each individual widget.
C++
#include <QApplication>
#include <QColor>
#include <QPalette>
int main(int argc, char* argv[])
{
QApplication app(argc, argv);
auto palette = app.palette();
QColor red(255, 0, 0);
palette.setColor(QPalette::PlaceholderText, red);
app.setPalette(palette);
...
return app.exec();
}
Python
import sys
from PyQt6 import QtGui, QtWidgets
ColorRole = QtGui.QPalette.ColorRole
def main():
app = QtWidgets.QApplication(sys.argv)
palette = app.palette()
red = QtGui.QColor(255, 0, 0)
palette.setColor(ColorRole.PlaceholderText, red)
app.setPalette(palette)
...
return app.exec()
Links
There is no way to set the default color of a link in a QLabel, QTextEdit, QPlainTextEdit, QTextBrowser, QMessageBox, etc. There are a few possible workarounds.
One is to set the link color when setting the label text, here, setting the label text to red. This will override the default color, and you can use a theme-dependent color to ensure the links are rendered properly.
label = QtWidgets.QLabel()
# Ensure it's displayed as a URL
label.setTextFormat(QtCore.Qt.TextFormat.RichText)
label.setText('<a href="https://google.com" style="color: red;">Google</a>')
However, this won't work with markdown input, and requires you to modify any existing text to include the styles, which is undesirable. A better solution is to set a default palette for ColorRole.Link.
C++
#include <QApplication>
#include <QColor>
#include <QPalette>
int main(int argc, char* argv[])
{
QApplication app(argc, argv);
auto palette = app.palette();
QColor red(255, 0, 0);
palette.setColor(QPalette::Active, QPalette::Link, red);
app.setPalette(palette);
...
return app.exec();
}
Python
import sys
from PyQt6 import QtGui, QtWidgets
ColorGroup = QtGui.QPalette.ColorGroup
ColorRole = QtGui.QPalette.ColorRole
def main():
app = QtWidgets.QApplication(sys.argv)
palette = app.palette()
red = QtGui.QColor(255, 0, 0)
palette.setColor(ColorGroup.Active, ColorRole.Link, red)
app.setPalette(palette)
...
return app.exec()
QToolButton
Menu Button Padding
QToolButton may have extra padding or clip the menu indicator in some cases. Auto-raised QToolButtons will clip the menu indicator, as will QToolButtons without text. Other cases will always add padding, whether there is a menu indicator or not. In order to force padding or no-padding for the menu indicator, set the Qt property of hasMenu to true or false. For example, to force additional padding for a menu indicator, use button->setProperty("hasMenu", true);.
A simple example of creating a QToolButton with text and with no menu drop-down is as follows:
C++
#include <QApplication>
#include <QString>
#include <QToolButton>
int main(int argc, char* argv[])
{
QApplication app(argc, argv);
... // Get our window, central widget, layout, etc.
auto *button = new QToolButton(widget);
button->setText(QString("Button 1"));
button->setProperty(QString("hasMenu"), false);
... // Add button to layout, show window, etc.
return app.exec();
}
Python
import sys
from PyQt6 import QtGui, QtWidgets
def main():
app = QtWidgets.QApplication(sys.argv)
... # Get our window, central widget, layout, etc.
button = QtWidgets.QToolButton(widget)
button.setText('Button 1')
button.setProperty('hasMenu', False)
... # Add button to layout, show window, etc.
return app.exec()
QCommandLink Icon
The default icon for QCommandLinkButton is platform-dependent, and depends on the standard icon SP_CommandLink (which cannot be specified in a stylesheet). See Standard Icons for an explanation on how to override this standard icon.
QWhatsThis
Tooltip Colors
QWhatsThis uses QPalette::toolTipText and QPalette::toolTipBase for its colors: unfortunately, these are not influenced by the stylesheet. To modify these, you can change the colors for QPalette::ToolTipBase and QPalette::ToolTipText. An example can be found in whatsthis.py.
A simple example of modifying the tooltip palette for the QWhatsThis style is as follows:
C++
#include <QApplication>
#include <QColor>
#include <QPalette>
int main(int argc, char* argv[])
{
QApplication app(argc, argv);
auto palette = app.palette();
QColor green(0, 255, 0);
QColor blue(0, 0, 255);
palette.setColor(QPalette::ToolTipBase, green);
palette.setColor(QPalette::ToolTipText, blue);
app.setPalette(palette);
...
return app.exec();
}
Python
import sys
from PyQt6 import QtGui, QtWidgets
ColorRole = QtGui.QPalette.ColorRole
def main():
app = QtWidgets.QApplication(sys.argv)
palette = app.palette()
green = QtGui.QColor(0, 255, 0)
blue = QtGui.QColor(0, 0, 255)
palette.setColor(ColorRole.ToolTipBase, green)
palette.setColor(ColorRole.ToolTipText, blue)
app.setPalette(palette)
...
return app.exec()
QWidget
Standard Icons
Certain standard icons cannot be overwritten in the stylesheet, and therefore a custom style must be installed in the Qt application. The standard-icons plugin comes with a set of custom standard icons, and the standard_icons.py example shows a complete application for how to override the default standard icons.
A simple example of overriding the command link icon for a PyQt6 application is as follows. First, configure with the standard-icons plugin.
python configure.py --extensions=standard-icons
Next, set the application stylesheet, subclass QCommonStyle to get custom standard icons, and install the style globally in the Qt application.
from PyQt6 import QtCore, QtGui, QtWidgets
StandardPixmap = QtWidgets.QStyle.StandardPixmap
OpenModeFlag = QtCore.QFile.OpenModeFlag
# Create a map of registered icons, so we can efficiently query if we
# should override the icon or use the pre-packaged standard icons.
ICON_MAP = {
...
StandardPixmap.SP_CommandLink: 'right_arrow.svg',
...
}
def stylesheet_icon(style, icon, option=None, widget=None):
'''Get a standard icon for the stylesheet style'''
# See if we've registered a custom icon in the stylesheet
path = ICON_MAP.get(icon, None)
if path is not None:
resource = f'dark:{path}'
if QtCore.QFile.exists(resource):
return QtGui.QIcon(resource)
# No custom icon: return the default for the style.
return QtWidgets.QCommonStyle.standardIcon(style, icon, option, widget)
class ApplicationStyle(QtWidgets.QCommonStyle):
def __init__(self, style):
super().__init__()
# Store an instance for the default style, so we can query that.
# Avoids an infinite, recursive loop.
self.style = style
def __getattribute__(self, item):
'''
Override for standardIcon. Everything else should default to the
system default. We cannot have `style_icon` be a member of
`ApplicationStyle`, since this will cause an infinite recursive loop.
'''
if item == 'standardIcon':
return lambda *x: stylesheet_icon(self, *x)
return getattr(self.style, item)
def main():
app = QtWidgets.QApplication(sys.argv)
# Install our custom style globally. QCommonStyle, unlike QProxyStyle,
# actually works nicely with stylesheets. `Fusion` is available
# on all platforms, but you can use any style you want. We
# just need a created style, because `app.style()` will be
# deleted by he garbage collector.
style = QtWidgets.QStyleFactory.create('Fusion')
app.setStyle(ApplicationStyle(style))
# Set our stylesheet.
# NOTE: this must occur after setting the application style.
file = QtCore.QFile('dark:stylesheet.qss')
file.open(OpenModeFlag.ReadOnly | OpenModeFlag.Text)
stream = QtCore.QTextStream(file)
app.setStyleSheet(stream.readAll())
...
return app.exec()