Version:            (using Devel)
Installed from:    Compiled sources
OS:                Linux

this is the backtrace:

Application: KWin (kwin), signal SIGSEGV
Using host libthread_db library "/lib/tls/i686/cmov/libthread_db.so.1".
[Thread debugging using libthread_db enabled]
[New Thread 0xb5d3f740 (LWP 16084)]
[KCrash handler]
#6  0xb7fa1d3a in KWin::Scene::Window::isOpaque ()
   from /opt/kde4/lib/libkdeinit4_kwin.so
#7  0xb7fa3b52 in KWin::Scene::paintSimpleScreen ()
   from /opt/kde4/lib/libkdeinit4_kwin.so
#8  0xb7fa1f8b in KWin::Scene::finalPaintScreen ()
   from /opt/kde4/lib/libkdeinit4_kwin.so
#9  0xb7fb32d4 in KWin::EffectsHandlerImpl::paintScreen ()
   from /opt/kde4/lib/libkdeinit4_kwin.so
#10 0xb3bb5794 in KWin::ShadowEffect::paintScreen ()
   from /opt/kde4/lib/kde4/kwin4_effect_builtins.so
#11 0xb7fb3271 in KWin::EffectsHandlerImpl::paintScreen ()
   from /opt/kde4/lib/libkdeinit4_kwin.so
#12 0xb3b97230 in KWin::PresentWindowsEffect::paintScreen ()
   from /opt/kde4/lib/kde4/kwin4_effect_builtins.so
#13 0xb7fb3271 in KWin::EffectsHandlerImpl::paintScreen ()
   from /opt/kde4/lib/libkdeinit4_kwin.so
#14 0xb7dad8c6 in KWin::Effect::paintScreen ()
   from /opt/kde4/lib/libkwineffects.so.1
#15 0xb7fb3271 in KWin::EffectsHandlerImpl::paintScreen ()
   from /opt/kde4/lib/libkdeinit4_kwin.so
#16 0xb7dad8c6 in KWin::Effect::paintScreen ()
   from /opt/kde4/lib/libkwineffects.so.1
#17 0xb7fb3271 in KWin::EffectsHandlerImpl::paintScreen ()
   from /opt/kde4/lib/libkdeinit4_kwin.so
#18 0xb3b8972c in KWin::BoxSwitchEffect::paintScreen ()
   from /opt/kde4/lib/kde4/kwin4_effect_builtins.so
#19 0xb7fb3271 in KWin::EffectsHandlerImpl::paintScreen ()
   from /opt/kde4/lib/libkdeinit4_kwin.so
#20 0xb3b8d6ff in KWin::DesktopGridEffect::paintScreen ()
   from /opt/kde4/lib/kde4/kwin4_effect_builtins.so
#21 0xb7fb3271 in KWin::EffectsHandlerImpl::paintScreen ()
   from /opt/kde4/lib/libkdeinit4_kwin.so
#22 0xb7dad8c6 in KWin::Effect::paintScreen ()
   from /opt/kde4/lib/libkwineffects.so.1
#23 0xb7fb3271 in KWin::EffectsHandlerImpl::paintScreen ()
   from /opt/kde4/lib/libkdeinit4_kwin.so
#24 0xb7dad8c6 in KWin::Effect::paintScreen ()
   from /opt/kde4/lib/libkwineffects.so.1
#25 0xb7fb3271 in KWin::EffectsHandlerImpl::paintScreen ()
   from /opt/kde4/lib/libkdeinit4_kwin.so
#26 0xb7dad8c6 in KWin::Effect::paintScreen ()
   from /opt/kde4/lib/libkwineffects.so.1
#27 0xb7fb3271 in KWin::EffectsHandlerImpl::paintScreen ()
   from /opt/kde4/lib/libkdeinit4_kwin.so
#28 0xb7dad8c6 in KWin::Effect::paintScreen ()
   from /opt/kde4/lib/libkwineffects.so.1
#29 0xb7fb3271 in KWin::EffectsHandlerImpl::paintScreen ()
   from /opt/kde4/lib/libkdeinit4_kwin.so
#30 0xb7dad8c6 in KWin::Effect::paintScreen ()
   from /opt/kde4/lib/libkwineffects.so.1
#31 0xb7fb3271 in KWin::EffectsHandlerImpl::paintScreen ()
   from /opt/kde4/lib/libkdeinit4_kwin.so
#32 0xb3ba611d in KWin::ZoomEffect::paintScreen ()
   from /opt/kde4/lib/kde4/kwin4_effect_builtins.so
#33 0xb7fb3271 in KWin::EffectsHandlerImpl::paintScreen ()
   from /opt/kde4/lib/libkdeinit4_kwin.so
#34 0xb7fa2dee in KWin::Scene::paintScreen ()
   from /opt/kde4/lib/libkdeinit4_kwin.so
#35 0xb7fad44d in KWin::SceneOpenGL::paint ()
   from /opt/kde4/lib/libkdeinit4_kwin.so
#36 0xb7f9e646 in KWin::Workspace::performCompositing ()
   from /opt/kde4/lib/libkdeinit4_kwin.so
#37 0xb7f42c49 in KWin::Workspace::qt_metacall ()
   from /opt/kde4/lib/libkdeinit4_kwin.so
#38 0xb7ad4fac in QMetaObject::activate (sender=0x80d883c, 
    from_signal_index=<value optimized out>, to_signal_index=4, argv=0x0)
    at /usr/src/kde4/qt-copy/src/corelib/kernel/qobject.cpp:3001
#39 0xb7ad53b2 in QMetaObject::activate (sender=0x80d883c, m=0xb7b60a64, 
    local_signal_index=0, argv=0x0)
    at /usr/src/kde4/qt-copy/src/corelib/kernel/qobject.cpp:3074
#40 0xb7b0d6c7 in QTimer::timeout (this=0x80d883c)
    at .moc/release-shared/moc_qtimer.cpp:126
#41 0xb7add93e in QTimer::timerEvent (this=0x80d883c, e=0xbfd612e8)
    at /usr/src/kde4/qt-copy/src/corelib/kernel/qtimer.cpp:263
#42 0xb7ad34e4 in QObject::event (this=0x80d883c, e=0xbfd612e8)
    at /usr/src/kde4/qt-copy/src/corelib/kernel/qobject.cpp:1105
#43 0xb72427ac in QApplicationPrivate::notify_helper (this=0x805a510, 
    receiver=0x80d883c, e=0xbfd612e8)
    at /usr/src/kde4/qt-copy/src/gui/kernel/qapplication.cpp:3735
#44 0xb72491c9 in QApplication::notify (this=0xbfd61574, receiver=0x80d883c, 
    e=0xbfd612e8)
    at /usr/src/kde4/qt-copy/src/gui/kernel/qapplication.cpp:3329
#45 0xb6f61ecd in KApplication::notify () from /opt/kde4/lib/libkdeui.so.5
#46 0xb7f581cd in KWin::Application::notify ()
   from /opt/kde4/lib/libkdeinit4_kwin.so
#47 0xb7ac4a89 in QCoreApplication::notifyInternal (this=0xbfd61574, 
    receiver=0x80d883c, event=0xbfd612e8)
    at /usr/src/kde4/qt-copy/src/corelib/kernel/qcoreapplication.cpp:582
#48 0xb7aed151 in QTimerInfoList::activateTimers (this=0x805d74c)
    at ../../include/QtCore/../../../../qt-copy/src/corelib/kernel/qcoreapplication.h:215
#49 0xb7aeac50 in timerSourceDispatch (source=0x805d718)
    at /usr/src/kde4/qt-copy/src/corelib/kernel/qeventdispatcher_glib.cpp:166
#50 0xb6929d16 in g_main_context_dispatch () from /usr/lib/libglib-2.0.so.0
#51 0xb692d0d3 in ?? () from /usr/lib/libglib-2.0.so.0
#52 0x0805ca98 in ?? ()
#53 0x00000000 in ?? ()
#0  0xffffe410 in __kernel_vsyscall ()