The backtrace:
Application: KolourPaint (kolourpaint), signal SIGSEGV
0x00007fce7a8c08d0 in __nanosleep_nocancel () from /lib/libc.so.6
Current language:  auto; currently c

Thread 1 (Thread 0x7fce7eaf5750 (LWP 5643)):
[KCrash Handler]
#5  0x0000000000000000 in ?? ()
#6  0x00007fce7b69d213 in QX11PaintEngine::drawPixmap (this=<value optimized out>, r=<value optimized out>, px=<value optimized out>, _sr=<value optimized out>) at painting/qpaintengine_x11.cpp:1865
#7  0x00007fce7b5d3716 in QPainter::drawPixmap (this=0x7fff86b2f440, p=<value optimized out>, pm=@0x7fff86b2f410) at painting/qpainter.cpp:5227
#8  0x00000000004749bf in QPainter::drawPixmap (this=0x7fff86b2f440, p=<value optimized out>, pm=@0x7fff86b2f410) at /usr/include/qt4/QtGui/qpainter.h:799
#9  0x0000000000475e68 in kpPixmapFX::ensureNoAlphaChannel (destPixmapPtr=0x7fff86b2f4d0)
    at /var/tmp/portage/kde-base/kolourpaint-4.2.0/work/kolourpaint-4.2.0/kolourpaint/pixmapfx/kpPixmapFX_MaskOps.cpp:255
#10 0x0000000000474626 in kpPixmapFX::convertToPixmap (image=@0x7fff86b2f6c0, pretty=<value optimized out>, wali=@0x7fff86b2f5b0)
    at /var/tmp/portage/kde-base/kolourpaint-4.2.0/work/kolourpaint-4.2.0/kolourpaint/pixmapfx/kpPixmapFX_FormatConversion.cpp:255
#11 0x0000000000476e03 in TransformPixmap (pm=<value optimized out>, transformMatrix_=<value optimized out>, backgroundColor=@0x1f06d50, targetWidth=-1, targetHeight=<value optimized out>)
    at /var/tmp/portage/kde-base/kolourpaint-4.2.0/work/kolourpaint-4.2.0/kolourpaint/pixmapfx/kpPixmapFX_Transforms.cpp:557
#12 0x00000000004772c7 in kpPixmapFX::rotate (pm=@0x7fff86b2f9c0, angle=<value optimized out>, backgroundColor=@0x1f06d50, targetWidth=-1, targetHeight=-1)
    at /var/tmp/portage/kde-base/kolourpaint-4.2.0/work/kolourpaint-4.2.0/kolourpaint/pixmapfx/kpPixmapFX_Transforms.cpp:754
#13 0x0000000000425d4e in kpTransformRotateCommand::execute (this=0x1f06d30)
    at /var/tmp/portage/kde-base/kolourpaint-4.2.0/work/kolourpaint-4.2.0/kolourpaint/commands/imagelib/transforms/kpTransformRotateCommand.cpp:105
#14 0x0000000000427b03 in kpCommandHistoryBase::addCommand (this=0x19914d0, command=0x1f06d30, execute=false)
    at /var/tmp/portage/kde-base/kolourpaint-4.2.0/work/kolourpaint-4.2.0/kolourpaint/commands/kpCommandHistoryBase.cpp:274
#15 0x0000000000467dad in kpMainWindow::addImageOrSelectionCommand (this=0x197dd40, cmd=0x1f06d30, addSelCreateCmdIfSelAvail=true, addSelContentCmdIfSelAvail=true)
    at /var/tmp/portage/kde-base/kolourpaint-4.2.0/work/kolourpaint-4.2.0/kolourpaint/mainWindow/kpMainWindow_Image.cpp:351
#16 0x000000000045ca65 in kpMainWindow::qt_metacall (this=0x197dd40, _c=QMetaObject::InvokeMetaMethod, _id=29881088, _a=0x7fff86b2fde0)
    at /var/tmp/portage/kde-base/kolourpaint-4.2.0/work/kolourpaint_build/kolourpaint/kpMainWindow.moc:407
#17 0x00007fce7c738f8d in QMetaObject::activate (sender=0x1995790, from_signal_index=<value optimized out>, to_signal_index=6, argv=0x1885ef0) at kernel/qobject.cpp:3052
#18 0x00007fce7b4bc187 in QAction::triggered (this=0x19a7720, _t1=false) at .moc/debug-shared/moc_qaction.cpp:236
#19 0x00007fce7b4bcef0 in QAction::activate (this=0x1995790, event=<value optimized out>) at kernel/qaction.cpp:1155
#20 0x00007fce7b8c431c in QMenuPrivate::activateCausedStack (this=0x1a28c60, causedStack=@0x7fff86b2ff00, action=0x1995790, action_e=QAction::Trigger, self=true) at widgets/qmenu.cpp:957
#21 0x00007fce7b8ca77b in QMenuPrivate::activateAction (this=0x1a28c60, action=0x1995790, action_e=27298176, self=true) at widgets/qmenu.cpp:1053
#22 0x00007fce7d5b1cf5 in KMenu::mouseReleaseEvent (this=0x1a08980, e=0x7fff86b30ab0) at /var/tmp/portage/kde-base/kdelibs-4.2.0-r3/work/kdelibs-4.2.0/kdeui/widgets/kmenu.cpp:454
#23 0x00007fce7b5148c0 in QWidget::event (this=0x1a08980, event=0x7fff86b30ab0) at kernel/qwidget.cpp:7511
#24 0x00007fce7b8cbd23 in QMenu::event (this=0x1a08980, e=0x7fff86b30ab0) at widgets/qmenu.cpp:2346
#25 0x00007fce7b4c1a9d in QApplicationPrivate::notify_helper (this=0x189b060, receiver=0x1a08980, e=0x7fff86b30ab0) at kernel/qapplication.cpp:4051
#26 0x00007fce7b4cad6d in QApplication::notify (this=<value optimized out>, receiver=0x1a08980, e=0x7fff86b30ab0) at kernel/qapplication.cpp:3753
#27 0x00007fce7d4f92a1 in KApplication::notify (this=0x7fff86b31810, receiver=0x1a08980, event=0x7fff86b30ab0)
    at /var/tmp/portage/kde-base/kdelibs-4.2.0-r3/work/kdelibs-4.2.0/kdeui/kernel/kapplication.cpp:307
#28 0x00007fce7c723963 in QCoreApplication::notifyInternal (this=0x7fff86b31810, receiver=0x1a08980, event=0x7fff86b30ab0) at kernel/qcoreapplication.cpp:590
#29 0x00007fce7b4c9ef2 in QApplicationPrivate::sendMouseEvent (receiver=0x1a08980, event=0x7fff86b30ab0, alienWidget=0x0, nativeWidget=0x1a08980, buttonDown=<value optimized out>, 
    lastMouseReceiver=@0x7fce7be86050) at ../../include/QtCore/../../src/corelib/kernel/qcoreapplication.h:211
#30 0x00007fce7b52ae2b in QETWidget::translateMouseEvent (this=0x1a08980, event=<value optimized out>) at kernel/qapplication_x11.cpp:4348
#31 0x00007fce7b529b15 in QApplication::x11ProcessEvent (this=0x7fff86b31810, event=0x7fff86b31450) at kernel/qapplication_x11.cpp:3532
#32 0x00007fce7b54efec in x11EventSourceDispatch (s=0x189e8d0, callback=0, user_data=0x0) at kernel/qguieventdispatcher_glib.cpp:141
#33 0x00007fce77113212 in IA__g_main_context_dispatch (context=0x189d1e0) at gmain.c:2144
#34 0x00007fce7711692d in g_main_context_iterate (context=0x189d1e0, block=1, dispatch=1, self=<value optimized out>) at gmain.c:2778
#35 0x00007fce77116aeb in IA__g_main_context_iteration (context=0x189d1e0, may_block=1) at gmain.c:2841
#36 0x00007fce7c74b49f in QEventDispatcherGlib::processEvents (this=0x189b2a0, flags=<value optimized out>) at kernel/qeventdispatcher_glib.cpp:318
#37 0x00007fce7b54e84f in QGuiEventDispatcherGlib::processEvents (this=0x19a7720, flags=<value optimized out>) at kernel/qguieventdispatcher_glib.cpp:197
#38 0x00007fce7c722602 in QEventLoop::processEvents (this=<value optimized out>, flags={i = -2035083456}) at kernel/qeventloop.cpp:144
#39 0x00007fce7c722795 in QEventLoop::exec (this=0x7fff86b31780, flags={i = -2035083376}) at kernel/qeventloop.cpp:191
#40 0x00007fce7c727356 in QCoreApplication::exec () at kernel/qcoreapplication.cpp:872
#41 0x000000000044e67c in main (argc=1, argv=0x7fff86b31d18) at /var/tmp/portage/kde-base/kolourpaint-4.2.0/work/kolourpaint-4.2.0/kolourpaint/kolourpaint.cpp:125

*** This bug has been marked as a duplicate of bug 183850 ***