Application that crashed: kwin
Version of the application: 4.3.2 (KDE 4.3.2)
KDE Version: 4.3.2 (KDE 4.3.2)
Qt Version: 4.5.3
Operating System: Linux 2.6.32 x86_64
Distribution: Debian GNU/Linux unstable (sid)

 -- Backtrace:
Application: KWin (kwin), signal: Segmentation fault
The current source language is "auto; currently c".
[KCrash Handler]
#5  QWidgetPrivate::close_helper (this=0x1, mode=QWidgetPrivate::CloseWithEvent) at kernel/qwidget.cpp:7109
#6  0x00007f5f53c7e6a2 in KWin::Workspace::closeActivePopup (this=0x239e300) at ../../kwin/useractions.cpp:312
#7  0x00007f5f53c816d0 in KWin::Workspace::showWindowMenu (this=0x239e300, pos=..., cl=<value optimized out>) at ../../kwin/useractions.cpp:1211
#8  0x00007f5f52a47c68 in KCommonDecoration::menuButtonPressed (this=0x28e0670) at ../../../kwin/lib/kcommondecoration.cpp:665
#9  0x00007f5f52a48fd3 in KCommonDecoration::qt_metacall (this=0x28e0670, _c=QMetaObject::InvokeMetaMethod, _id=<value optimized out>, _a=0x7fffa6ccc770) at ./kcommondecoration.moc:111
#10 0x00007f5f4fc15df2 in QMetaObject::activate (sender=0x289fbc0, from_signal_index=<value optimized out>, to_signal_index=27, argv=0x387d0) at kernel/qobject.cpp:3112
#11 0x00007f5f506b4efe in QAbstractButtonPrivate::emitPressed (this=0x2900da0) at widgets/qabstractbutton.cpp:557
#12 0x00007f5f506b50d3 in QAbstractButton::mousePressEvent (this=0x289fbc0, e=0x7fffa6ccc810) at widgets/qabstractbutton.cpp:1092
#13 0x00007f5f52a472eb in KCommonDecorationButton::mousePressEvent (this=0x289fbc0, e=<value optimized out>) at ../../../kwin/lib/kcommondecoration.cpp:992
#14 0x00007f5f50394556 in QWidget::event (this=0x289fbc0, event=0x7fffa6ccd130) at kernel/qwidget.cpp:7550
#15 0x00007f5f5034401d in QApplicationPrivate::notify_helper (this=0x229f2b0, receiver=0x289fbc0, e=0x7fffa6ccd130) at kernel/qapplication.cpp:4065
#16 0x00007f5f5034c7ca in QApplication::notify (this=<value optimized out>, receiver=0x289fbc0, e=0x7fffa6ccd130) at kernel/qapplication.cpp:3767
#17 0x00007f5f534c80db in KApplication::notify (this=0x7fffa6cceef0, receiver=0x289fbc0, event=0x7fffa6ccd130) at ../../kdeui/kernel/kapplication.cpp:302
#18 0x00007f5f4fc00c9c in QCoreApplication::notifyInternal (this=0x7fffa6cceef0, receiver=0x289fbc0, event=0x7fffa6ccd130) at kernel/qcoreapplication.cpp:610
#19 0x00007f5f5034ba78 in QCoreApplication::sendSpontaneousEvent (receiver=0x289fbc0, event=0x7fffa6ccd130, alienWidget=0x0, nativeWidget=0x289fbc0, buttonDown=<value optimized out>, 
    lastMouseReceiver=...) at ../../include/QtCore/../../src/corelib/kernel/qcoreapplication.h:216
#20 QApplicationPrivate::sendMouseEvent (receiver=0x289fbc0, event=0x7fffa6ccd130, alienWidget=0x0, nativeWidget=0x289fbc0, buttonDown=<value optimized out>, lastMouseReceiver=...)
    at kernel/qapplication.cpp:2924
#21 0x00007f5f503b4659 in QETWidget::translateMouseEvent (this=0x289fbc0, event=<value optimized out>) at kernel/qapplication_x11.cpp:4411
#22 0x00007f5f503b340f in QApplication::x11ProcessEvent (this=0x7fffa6cceef0, event=0x7fffa6cceb00) at kernel/qapplication_x11.cpp:3552
#23 0x00007f5f503db76c in x11EventSourceDispatch (s=0x22a30b0, callback=0, user_data=0x0) at kernel/qguieventdispatcher_glib.cpp:146
#24 0x00007f5f4a5e113a in g_main_context_dispatch () from /lib/libglib-2.0.so.0
#25 0x00007f5f4a5e4998 in ?? () from /lib/libglib-2.0.so.0
#26 0x00007f5f4a5e4b4c in g_main_context_iteration () from /lib/libglib-2.0.so.0
#27 0x00007f5f4fc2939c in QEventDispatcherGlib::processEvents (this=0x22856a0, flags=<value optimized out>) at kernel/qeventdispatcher_glib.cpp:407
#28 0x00007f5f503daf1f in QGuiEventDispatcherGlib::processEvents (this=0x1, flags=<value optimized out>) at kernel/qguieventdispatcher_glib.cpp:202
#29 0x00007f5f4fbff562 in QEventLoop::processEvents (this=<value optimized out>, flags=...) at kernel/qeventloop.cpp:149
#30 0x00007f5f4fbff934 in QEventLoop::exec (this=0x7fffa6ccee30, flags=...) at kernel/qeventloop.cpp:201
#31 0x00007f5f4fc01ba4 in QCoreApplication::exec () at kernel/qcoreapplication.cpp:888
#32 0x00007f5f53c59ae8 in kdemain (argc=3, argv=0x7fffa6ccf3e8) at ../../kwin/main.cpp:522
#33 0x00007f5f538dfabd in __libc_start_main (main=<value optimized out>, argc=<value optimized out>, ubp_av=<value optimized out>, init=<value optimized out>, fini=<value optimized out>, 
    rtld_fini=<value optimized out>, stack_end=0x7fffa6ccf3d8) at libc-start.c:222
#34 0x0000000000400649 in _start () at ../sysdeps/x86_64/elf/start.S:113

Reported using DrKonqi