Application: kwin (4.8.00 (4.8.0))
KDE Platform Version: 4.8.00 (4.8.0) (Compiled from sources)
Qt Version: 4.8.0
Operating System: Linux 3.2.5-vs2.3.2.6-hardened x86_64
Distribution (Platform): Gentoo Packages

-- Information about the crash:
- What I was doing when the application crashed:
after some minutes of inactivity re-activated the composition with alt+shift+F12
then bringing the mouse to the corner activating the present windows effect
selected one window
kwin crash

- Unusual behavior I noticed:
notably firefox was totally black and unresponsive _before_ re-activation of compostion and it  was still closing when the kwin crash happened

this is the content of debug area 1212, kwin pid was probably 10562

[...]
kwin(10562) KDecorationPlugins::loadPlugin: kwin : path  "/usr/lib64/kde4/kwin3_oxygen.so"  for  "kwin3_oxygen"
kwin(10562) KWin::Extensions::init: Extensions: shape: 0x "11"  composite: 0x "4"  render: 0x "b"  fixes: 0x "50"  non_native_pixmaps:  false
kwin(10562) KWin::Workspace::setupCompositing: Compositing is suspended
kwin(10562) KWin::Workspace::updateClientArea: screens:  1 desktops:  3
kwin(10562) KWin::Workspace::updateClientArea: Done.
kwin(10562) KWin::Workspace::updateClientArea: screens:  1 desktops:  3
kwin(10562) KWin::Workspace::updateClientArea: Done.
[...]
kwin(10562) KWin::Workspace::updateClientArea: screens:  1 desktops:  3
kwin(10562) KWin::Workspace::updateClientArea: Done.
kwin(10562) KWin::Workspace::updateClientArea: screens:  1 desktops:  3
kwin(10562) KWin::Workspace::updateClientArea: Done.
kwin(10562) KWin::Workspace::updateClientArea: screens:  1 desktops:  3
kwin(10562) KWin::Workspace::updateClientArea: Done.
kwin(10562) KWin::Client::readUserTimeMapTimestamp: User timestamp, ASN: 5494303
kwin(10562) KWin::Client::readUserTimeMapTimestamp: User timestamp, final: 'ID: 25166075 ;WMCLASS: "krunner" : "krunner" ;Caption: "Esegui comando" ' : 5494303
kwin(10562) KWin::Workspace::allowClientActivation: Activation, compared: 'ID: 25166075 ;WMCLASS: "krunner" : "krunner" ;Caption: "Esegui comando" ' : 5494303 : 5494063 : true
kwin(10562) KWin::Workspace::updateClientArea: screens:  1 desktops:  3
kwin(10562) KWin::Workspace::updateClientArea: Done.
kwin(10562) KWin::Client::configureRequest: KWin::Client(0x3002828210) true false false
kwin(10562) KWin::Client::configureRequest: PERMITTED 'ID: 25166075 ;WMCLASS: "krunner" : "krunner" ;Caption: "Esegui comando" ' true
kwin(10562) KWin::Workspace::updateClientArea: screens:  1 desktops:  3
kwin(10562) KWin::Workspace::updateClientArea: Done.
kwin(10562) KWin::Client::readUserTimeMapTimestamp: User timestamp, ASN: 4294967295
kwin(10562) KWin::Client::readUserTimeMapTimestamp: User timestamp, final: 'ID: 88080410 ;WMCLASS: "kate" : "kate" ;Caption: "digikam-devel: file:///home/vivo/digikam-devel/README_devel_setup â Kate" ' : 5542260
kwin(10562) KWin::Workspace::allowClientActivation: Activation, compared: 'ID: 88080410 ;WMCLASS: "kate" : "kate" ;Caption: "digikam-devel: file:///home/vivo/digikam-devel/README_devel_setup â Kate" ' : 5542260 : 5542150 : true
kwin(10562) KWin::Workspace::updateClientArea: screens:  1 desktops:  3
kwin(10562) KWin::Workspace::updateClientArea: Done.
kwin(10562) KWin::Workspace::updateClientArea: screens:  1 desktops:  3
kwin(10562) KWin::Workspace::updateClientArea: Done.
kwin(10562) KWin::Client::readUserTimeMapTimestamp: User timestamp, ASN: 5537475
kwin(10562) KWin::Client::readUserTimeMapTimestamp: User timestamp, final: 'ID: 88080524 ;WMCLASS: "kate" : "kate" ;Caption: "Errori o avvertimenti durante l'apertura dei documenti â Kate" ' : 5537475
kwin(10562) KWin::Workspace::allowClientActivation: Activation: Belongs to active application
kwin(10562) KWin::Workspace::updateClientArea: screens:  1 desktops:  3
kwin(10562) KWin::Workspace::updateClientArea: Done.
kwin(10562) KWin::Workspace::allowFullClientRaising: Raising: Belongs to active application
kwin(10562) KWin::Workspace::allowFullClientRaising: Raising: Belongs to active application
kwin(10562) KWin::Workspace::updateClientArea: screens:  1 desktops:  3
kwin(10562) KWin::Workspace::updateClientArea: Done.
kwin(10562) KWin::Extensions::init: Extensions: shape: 0x "11"  composite: 0x "4"  render: 0x "b"  fixes: 0x "50"  non_native_pixmaps:  false
kwin(10562) KWin::Extensions::init: Extensions: shape: 0x "11"  composite: 0x "4"  render: 0x "b"  fixes: 0x "50"  non_native_pixmaps:  false
kwin(10562) KWin::CompositingPrefs::detect: glx version is  1 . 4
kwin(10562) KWin::Workspace::setupCompositing: Initializing OpenGL compositing
kwin(10562) KWin::SceneOpenGL::initBufferConfigs: Drawable visual (depth  24 ): 0x "31a"
kwin(10562) KWin::SceneOpenGL::initBufferConfigs: Drawable visual (depth  32 ): 0x "76"
kwin(10562) KWin::SceneOpenGL::initBuffer: Buffer visual (depth  24 ): 0x "32a"
kwin(10562) KWin::ShaderManager::initShaders: Ortho Shader is valid
kwin(10562) KWin::ShaderManager::initShaders: Generic Shader is valid
kwin(10562) KWin::ShaderManager::initShaders: Color Shader is valid
kwin(10562) KWin::SceneOpenGL::SceneOpenGL: DB: true , Direct: true
kwin(10562) KWin::currentRefreshRate: Refresh rate  60 Hz
kwin(10562) KWin::EffectsHandlerImpl::loadEffect: Trying to load  "kwin4_effect_slidingpopups"
kwin(10562) KWin::EffectsHandlerImpl::loadEffect: Trying to load  "kwin4_effect_fade"
kwin(10562) KWin::EffectsHandlerImpl::loadEffect: Trying to load  "kwin4_effect_desktopgrid"
kwin(10562) KWin::EffectsHandlerImpl::loadEffect: Trying to load  "kwin4_effect_fadedesktop"
kwin(10562) KWin::EffectsHandlerImpl::loadEffect: Trying to load  "kwin4_effect_presentwindows"
kwin(10562) KWin::EffectsHandlerImpl::loadEffect: Trying to load  "kwin4_effect_dashboard"
kwin(10562) KWin::EffectsHandlerImpl::loadEffect: Trying to load  "kwin4_effect_login"
kwin(10562) KWin::EffectsHandlerImpl::loadEffect: Trying to load  "kwin4_effect_startupfeedback"
kwin(10562) KWin::EffectsHandlerImpl::loadEffect: Trying to load  "kwin4_effect_outline"
kwin(10562) KWin::EffectsHandlerImpl::loadEffect: Trying to load  "kwin4_effect_boxswitch"
kwin(10562) KWin::EffectsHandlerImpl::loadEffect: Trying to load  "kwin4_effect_taskbarthumbnail"
kwin(10562) KWin::EffectsHandlerImpl::loadEffect: Trying to load  "kwin4_effect_logout"
kwin(10562) KWin::EffectsHandlerImpl::loadEffect: Trying to load  "kwin4_effect_screenshot"
kwin(10562) KWin::EffectsHandlerImpl::loadEffect: Trying to load  "kwin4_effect_translucency"
kwin(10562) KWin::EffectsHandlerImpl::loadEffect: Trying to load  "kwin4_effect_highlightwindow"
kwin(10562) KWin::EffectsHandlerImpl::loadEffect: Trying to load  "kwin4_effect_zoom"
kwin(10562) KWin::EffectsHandlerImpl::loadEffect: Trying to load  "kwin4_effect_dialogparent"
kwin(10562) KWin::EffectsHandlerImpl::loadEffect: Trying to load  "kwin4_effect_minimizeanimation"
kwin(10562) KWin::EffectsHandlerImpl::loadEffect: Trying to load  "kwin4_effect_coverswitch"
kwin(10562) KWin::Client::pingTimeout: Ping timeout: "Re: [Lcms-user] accessing (all) tags from a profile - Mozilla Firefox"
kwin(10562) KWin::Client::killProcess: Kill process: 11963 ( "localhost" )
kwin(10562) KWin::Client::readUserTimeMapTimestamp: User timestamp, ASN: 7093626
kwin(10562) KWin::Client::readUserTimeMapTimestamp: User timestamp, final: 'ID: 92274706 ;WMCLASS: "kwin_killer_helper" : "kwin_killer_helper" ;Caption: "Avvertimento â KWin" ' : 7093626
kwin(10562) KWin::Workspace::allowClientActivation: Activation, compared: 'ID: 92274706 ;WMCLASS: "kwin_killer_helper" : "kwin_killer_helper" ;Caption: "Avvertimento â KWin" ' : 7093626 : 7096159 : false
kwin(10562) KWin::Workspace::updateClientArea: screens:  1 desktops:  3
kwin(10562) KWin::Workspace::updateClientArea: Done.

kwin(12875) KDecorationPlugins::loadPlugin: kwin : path  "/usr/lib64/kde4/kwin3_oxygen.so"  for  "kwin3_oxygen"
[...]

The crash does not seem to be reproducible.

-- Backtrace:
Application: KWin (kwin), signal: Segmentation fault
Using host libthread_db library "/lib64/libthread_db.so.1".
82	T_PSEUDO (SYSCALL_SYMBOL, SYSCALL_NAME, SYSCALL_NARGS)
[KCrash Handler]
#6  0x0000032950a4e5f4 in QWidget::hide (this=0x0) at /usr/include/qt4/QtGui/qwidget.h:498
#7  0x0000032950a41fe4 in KWin::PresentWindowsEffect::setHighlightedWindow (this=0x3002bd73c0, w=0x3002568450) at /var/tmp/portage/kde-base/kwin-9999/work/kwin-9999/kwin/effects/presentwindows/presentwindows.cpp:1806
#8  0x0000032950a4b203 in KWin::PresentWindowsEffect::slotWindowClosed (this=0x3002bd73c0, w=0x300240a5a0) at /var/tmp/portage/kde-base/kwin-9999/work/kwin-9999/kwin/effects/presentwindows/presentwindows.cpp:475
#9  0x0000032976e8e117 in QMetaObject::activate (sender=0x3002b94af0, m=<optimized out>, local_signal_index=<optimized out>, argv=0x3e921c44760) at kernel/qobject.cpp:3547
#10 0x000003297820b0a2 in KWin::EffectsHandler::windowClosed (this=<optimized out>, _t1=0x300240a5a0) at /var/tmp/portage/kde-base/kwin-9999/work/kwin-9999_build/kwin/libkwineffects/kwineffects.moc:260
#11 0x0000032976e8e117 in QMetaObject::activate (sender=0x30026fa820, m=<optimized out>, local_signal_index=<optimized out>, argv=0x3e921c448d0) at kernel/qobject.cpp:3547
#12 0x000003297bf1f12f in KWin::Toplevel::windowClosed (this=<optimized out>, _t1=0x30026fa820, _t2=0x3002637340) at /var/tmp/portage/kde-base/kwin-9999/work/kwin-9999_build/kwin/toplevel.moc:326
#13 0x000003297beac31e in KWin::Client::releaseWindow (this=0x30026fa820, on_shutdown=false) at /var/tmp/portage/kde-base/kwin-9999/work/kwin-9999/kwin/client.cpp:247
#14 0x000003297becf6e9 in KWin::Client::windowEvent (this=0x30026fa820, e=0x3e921c451a0) at /var/tmp/portage/kde-base/kwin-9999/work/kwin-9999/kwin/events.cpp:584
#15 0x000003297becf987 in KWin::Workspace::workspaceEvent (this=0x30023be160, e=0x3e921c451a0) at /var/tmp/portage/kde-base/kwin-9999/work/kwin-9999/kwin/events.cpp:295
#16 0x000003297bec2a59 in KWin::Application::x11EventFilter (this=0x3e921c45480, e=0x3e921c451a0) at /var/tmp/portage/kde-base/kwin-9999/work/kwin-9999/kwin/main.cpp:359
#17 0x0000032975f9f815 in qt_x11EventFilter (ev=0x3e921c451a0) at kernel/qapplication_x11.cpp:435
#18 qt_x11EventFilter (ev=0x3e921c451a0) at kernel/qapplication_x11.cpp:423
#19 0x0000032975facb16 in QApplication::x11ProcessEvent (this=0x3e921c45480, event=0x3e921c451a0) at kernel/qapplication_x11.cpp:3332
#20 0x0000032975fd7051 in QEventDispatcherX11::processEvents (this=0x30021cc9b0, flags=...) at kernel/qeventdispatcher_x11.cpp:132
#21 0x0000032976e768c2 in QEventLoop::processEvents (this=<optimized out>, flags=...) at kernel/qeventloop.cpp:149
#22 0x0000032976e76b07 in QEventLoop::exec (this=0x3e921c45410, flags=...) at kernel/qeventloop.cpp:204
#23 0x0000032976e7c047 in QCoreApplication::exec () at kernel/qcoreapplication.cpp:1148
#24 0x000003297bec4674 in kdemain (argc=1, argv=<optimized out>) at /var/tmp/portage/kde-base/kwin-9999/work/kwin-9999/kwin/main.cpp:541
#25 0x000003297495732d in __libc_start_main (main=0x3001fbfa90 <main(int, char**)>, argc=1, ubp_av=0x3e921c45af8, init=<optimized out>, fini=<optimized out>, rtld_fini=<optimized out>, stack_end=0x3e921c45ae8) at libc-start.c:234
#26 0x0000003001fbfaed in _start ()

Reported using DrKonqi