Version:            (using KDE 4.4.3)
Installed from:    Gentoo Packages

Kwin crash after right click, the backtrace:
Application: KWin (kwin), signal: Segmentation fault
Traceback (most recent call last):
  File "/usr/share/gdb/auto-load/usr/lib64/libgobject-2.0.so.0.2200.5-gdb.py", line 9, in <module>
    from gobject import register
  File "/usr/share/glib-2.0/gdb/gobject.py", line 3, in <module>
    import gdb.backtrace
ImportError: No module named backtrace
The current source language is "auto; currently asm".
[KCrash Handler]
#5  QBasicAtomicInt::ref (this=0x0) at /usr/include/qt4/QtCore/qatomic_x86_64.h:121
#6  0x00007fef9c16c059 in operator+ (s1=..., s2=...) at /usr/include/qt4/QtCore/qstring.h:1010
#7  0x00007fef9c1631f3 in KWin::Client::caption (this=<value optimized out>, full=<value optimized out>) at /var/tmp/portage/kde-base/kwin-4.4.3/work/kwin-4.4.3/kwin/client.cpp:1670
#8  0x00007fef9c1bcf51 in KWin::Workspace::groupTabPopupAboutToShow (this=0x16d58e0) at /var/tmp/portage/kde-base/kwin-4.4.3/work/kwin-4.4.3/kwin/useractions.cpp:402
#9  0x00007fef9c1527a4 in KWin::Workspace::qt_metacall (this=0x16d58e0, _c=QMetaObject::InvokeMetaMethod, _id=<value optimized out>, _a=0x7fff0530f990)
    at /var/tmp/portage/kde-base/kwin-4.4.3/work/kwin-4.4.3_build/kwin/workspace.moc:513
#10 0x00007fef9a1a411f in QMetaObject::activate (sender=0x9cfe070, m=<value optimized out>, local_signal_index=<value optimized out>, argv=0x2) at kernel/qobject.cpp:3285
#11 0x00007fef99442da3 in QMenu::popup (this=0x9cfe070, p=..., atAction=0x0) at widgets/qmenu.cpp:1823
#12 0x00007fef994457fe in QMenu::internalDelayedPopup (this=0x2fca2d0) at widgets/qmenu.cpp:3007
#13 0x00007fef99445d7b in QMenu::timerEvent (this=0x2fca2d0, e=<value optimized out>) at widgets/qmenu.cpp:2848
#14 0x00007fef9a19f5e3 in QObject::event (this=0x2fca2d0, e=0x2538e30) at kernel/qobject.cpp:1204
#15 0x00007fef98fd41cd in QWidget::event (this=0x2fca2d0, event=0x7fff05310730) at kernel/qwidget.cpp:8455
#16 0x00007fef9944896b in QMenu::event (this=0x2fca2d0, e=0x7fff05310730) at widgets/qmenu.cpp:2414
#17 0x00007fef98f6b5c1 in QApplicationPrivate::notify_helper (this=0x140a5e0, receiver=0x2fca2d0, e=0x7fff05310730) at kernel/qapplication.cpp:4300
#18 0x00007fef98f72742 in QApplication::notify (this=0x7fff053120e0, receiver=0x2fca2d0, e=0x7fff05310730) at kernel/qapplication.cpp:4265
#19 0x00007fef9ae55141 in KApplication::notify (this=0x7fff053120e0, receiver=0x2fca2d0, event=0x7fff05310730)
    at /var/tmp/portage/kde-base/kdelibs-4.4.3/work/kdelibs-4.4.3/kdeui/kernel/kapplication.cpp:302
#20 0x00007fef9a18c08b in QCoreApplication::notifyInternal (this=0x7fff053120e0, receiver=0x2fca2d0, event=0x7fff05310730) at kernel/qcoreapplication.cpp:704
#21 0x00007fef9a1c1a94 in QCoreApplication::sendEvent (this=0x140e2a0) at kernel/qcoreapplication.h:215
#22 QTimerInfoList::activateTimers (this=0x140e2a0) at kernel/qeventdispatcher_unix.cpp:603
#23 0x00007fef9a1bdb18 in timerSourceDispatch (source=<value optimized out>) at kernel/qeventdispatcher_glib.cpp:184
#24 idleTimerSourceDispatch (source=<value optimized out>) at kernel/qeventdispatcher_glib.cpp:231
#25 0x00007fef95a1c649 in g_main_dispatch (context=0x140c940) at gmain.c:1960
#26 IA__g_main_context_dispatch (context=0x140c940) at gmain.c:2513
#27 0x00007fef95a203a8 in g_main_context_iterate (context=0x140c940, block=1, dispatch=1, self=<value optimized out>) at gmain.c:2591
#28 0x00007fef95a2056c in IA__g_main_context_iteration (context=0x140c940, may_block=1) at gmain.c:2654
#29 0x00007fef9a1bd71c in QEventDispatcherGlib::processEvents (this=0x140a570, flags=<value optimized out>) at kernel/qeventdispatcher_glib.cpp:412
#30 0x00007fef99037faf in QGuiEventDispatcherGlib::processEvents (this=0x0, flags=<value optimized out>) at kernel/qguieventdispatcher_glib.cpp:204
#31 0x00007fef9a18a572 in QEventLoop::processEvents (this=<value optimized out>, flags=...) at kernel/qeventloop.cpp:149
#32 0x00007fef9a18aa14 in QEventLoop::exec (this=0x7fff053109e0, flags=...) at kernel/qeventloop.cpp:201
#33 0x00007fef994436f5 in QMenu::exec (this=<value optimized out>, p=..., action=0x0) at widgets/qmenu.cpp:2063
#34 0x00007fef9c1beca5 in KWin::Workspace::showWindowMenu (this=0x16d58e0, pos=..., cl=<value optimized out>) at /var/tmp/portage/kde-base/kwin-4.4.3/work/kwin-4.4.3/kwin/useractions.cpp:1595
#35 0x00007fef9c16f201 in KWin::Workspace::showWindowMenu (this=0x16d58e0, pos=..., cl=0xa1032e0) at /var/tmp/portage/kde-base/kwin-4.4.3/work/kwin-4.4.3/kwin/workspace.h:1107
#36 0x00007fef898f987e in Oxygen::OxygenClient::mousePressEvent (this=0x2338af0, event=<value optimized out>)
    at /var/tmp/portage/kde-base/kwin-4.4.3/work/kwin-4.4.3/kwin/clients/oxygen/oxygenclient.cpp:1470
#37 0x00007fef898f9b79 in Oxygen::OxygenClient::eventFilter (this=0x2338af0, object=0x8b7a550, event=0x7fff05311510)
    at /var/tmp/portage/kde-base/kwin-4.4.3/work/kwin-4.4.3/kwin/clients/oxygen/oxygenclient.cpp:1267
#38 0x00007fef9a18b887 in QCoreApplicationPrivate::sendThroughObjectEventFilters (this=<value optimized out>, receiver=0x8b7a550, event=0x7fff05311510) at kernel/qcoreapplication.cpp:819
#39 0x00007fef98f6b5ac in QApplicationPrivate::notify_helper (this=0x140a5e0, receiver=0x8b7a550, e=0x7fff05311510) at kernel/qapplication.cpp:4296
#40 0x00007fef98f7343e in QApplication::notify (this=<value optimized out>, receiver=0x8b7a550, e=0x7fff05311510) at kernel/qapplication.cpp:3865
#41 0x00007fef9ae55141 in KApplication::notify (this=0x7fff053120e0, receiver=0x8b7a550, event=0x7fff05311510)
    at /var/tmp/portage/kde-base/kdelibs-4.4.3/work/kdelibs-4.4.3/kdeui/kernel/kapplication.cpp:302
#42 0x00007fef9a18c08b in QCoreApplication::notifyInternal (this=0x7fff053120e0, receiver=0x8b7a550, event=0x7fff05311510) at kernel/qcoreapplication.cpp:704
#43 0x00007fef98f71ef1 in QCoreApplication::sendEvent (receiver=0x8b7a550, event=0x7fff05311510, alienWidget=0x0, nativeWidget=0x8b7a550, buttonDown=<value optimized out>, lastMouseReceiver=..., 
    spontaneous=true) at ../../include/QtCore/../../src/corelib/kernel/qcoreapplication.h:215
#44 QApplicationPrivate::sendMouseEvent (receiver=0x8b7a550, event=0x7fff05311510, alienWidget=0x0, nativeWidget=0x8b7a550, buttonDown=<value optimized out>, lastMouseReceiver=..., spontaneous=true)
    at kernel/qapplication.cpp:2965
#45 0x00007fef9900c910 in QETWidget::translateMouseEvent (this=0x8b7a550, event=<value optimized out>) at kernel/qapplication_x11.cpp:4368
#46 0x00007fef9900ba8c in QApplication::x11ProcessEvent (this=0x7fff053120e0, event=0x7fff05311cf0) at kernel/qapplication_x11.cpp:3501
#47 0x00007fef990384b2 in x11EventSourceDispatch (s=0x140e370, callback=0, user_data=0x0) at kernel/qguieventdispatcher_glib.cpp:146
#48 0x00007fef95a1c649 in g_main_dispatch (context=0x140c940) at gmain.c:1960
#49 IA__g_main_context_dispatch (context=0x140c940) at gmain.c:2513
#50 0x00007fef95a203a8 in g_main_context_iterate (context=0x140c940, block=1, dispatch=1, self=<value optimized out>) at gmain.c:2591
#51 0x00007fef95a2056c in IA__g_main_context_iteration (context=0x140c940, may_block=1) at gmain.c:2654
#52 0x00007fef9a1bd71c in QEventDispatcherGlib::processEvents (this=0x140a570, flags=<value optimized out>) at kernel/qeventdispatcher_glib.cpp:412
#53 0x00007fef99037faf in QGuiEventDispatcherGlib::processEvents (this=0x0, flags=<value optimized out>) at kernel/qguieventdispatcher_glib.cpp:204
#54 0x00007fef9a18a572 in QEventLoop::processEvents (this=<value optimized out>, flags=...) at kernel/qeventloop.cpp:149
#55 0x00007fef9a18aa14 in QEventLoop::exec (this=0x7fff05312020, flags=...) at kernel/qeventloop.cpp:201
#56 0x00007fef9a18d444 in QCoreApplication::exec () at kernel/qcoreapplication.cpp:981
#57 0x00007fef9c17a92b in kdemain (argc=3, argv=0x7fff053125e8) at /var/tmp/portage/kde-base/kwin-4.4.3/work/kwin-4.4.3/kwin/main.cpp:526
#58 0x00007fef960f9ba6 in __libc_start_main (main=0x400a40 <main>, argc=3, ubp_av=0x7fff053125e8, init=0x400aa0 <__libc_csu_init>, fini=<value optimized out>, rtld_fini=<value optimized out>, 
    stack_end=0x7fff053125d8) at libc-start.c:220
#59 0x0000000000400969 in _start () at ../sysdeps/x86_64/elf/start.S:113