Segmentation fault in drawComplexControl() with Gtk style (Qt 4.8.1)

[toralf]

After upgrading to Qt 4.8.1, the application I'm working on got very unstable if the Gtk style (which is my default) is used - I get frequent segfaults for simple operations. The first few call stack entries when this occurs are:

#0 0x00000000 in ?? ()
#1 0x00e7d178 in QGtkStyle::drawComplexControl(QStyle::ComplexControl, QStyleOptionComplex const*, QPainter*, QWidget const*) const ()
from /usr/lib/qt4/lib/libQtGui.so.4
#2 0x00f82ae5 in QScrollBar::paintEvent(QPaintEvent*) ()
from /usr/lib/qt4/lib/libQtGui.so.4
#3 0x00ad1494 in QWidget::event(QEvent*) () from /usr/lib/qt4/lib/libQtGui.so.4
#4 0x00ece894 in QAbstractSlider::event(QEvent*) ()

It turns out that I can also reproduce this problem with (at least) one of the example applications - the "tabdialog". Steps to reproduce become:

Make sure "GTK+" is selected as GUI Style in Qt Configuration, or alternatively, "Desktop Settings" on a GNOME based system.

/usr/lib/qt4/examples/dialogs/tabdialog/tabdialog (but substitute your Qt root for /usr/lib/qt4 as appropriate.)

Select the "Applications" tab.

This result in the good (or bad) old
Segmentation fault (core dumped)

That's on a system running CentOS 5.8, 32-bit.

Does anyone else have this problem?

[alleym1]

My Debian 5.0 build also produces this exact core file whenever I attempt to launch a Qt binary (designer, linguist, assistant).

[toralf]

Right. Thanks.

I've now filed a bug report for this: https://bugreports.qt-project.org/browse/QTBUG-25760

I've looked at the Qt source code, too, and I think I know how the problem could be fixed. I'll add more details to the QtBug...