Application: kwin_x11 (5.8.5)

Qt Version: 5.7.1
Frameworks Version: 5.29.0
Operating System: Linux 4.4.41-1-MANJARO x86_64
Distribution: "Manjaro Linux"

-- Information about the crash:
- What I was doing when the application crashed:
I was using the alt-tab window switcher, but it did not work at all, after the crash kde went to what I think is KDE/Openbox.

-- Backtrace:
Application: KWin (kwin_x11), signal: Segmentation fault
Using host libthread_db library "/usr/lib/libthread_db.so.1".
[Current thread is 1 (Thread 0x7f5330f92840 (LWP 8998))]

Thread 5 (Thread 0x7f52fd331700 (LWP 9011)):
#0  0x00007f5329c5610f in pthread_cond_wait@@GLIBC_2.3.2 () at /usr/lib/libpthread.so.0
#1  0x00007f532cfcc1f4 in  () at /usr/lib/libQt5Script.so.5
#2  0x00007f532cfcc239 in  () at /usr/lib/libQt5Script.so.5
#3  0x00007f5329c50454 in start_thread () at /usr/lib/libpthread.so.0
#4  0x00007f53309e07df in clone () at /usr/lib/libc.so.6

Thread 4 (Thread 0x7f530dbef700 (LWP 9008)):
#0  0x00007f53309d7551 in ppoll () at /usr/lib/libc.so.6
#1  0x00007f532e0865f9 in qt_safe_poll(pollfd*, unsigned long, timespec const*) () at /usr/lib/libQt5Core.so.5
#2  0x00007f532e087efa in QEventDispatcherUNIX::processEvents(QFlags<QEventLoop::ProcessEventsFlag>) () at /usr/lib/libQt5Core.so.5
#3  0x00007f532e034d3a in QEventLoop::exec(QFlags<QEventLoop::ProcessEventsFlag>) () at /usr/lib/libQt5Core.so.5
#4  0x00007f532de57063 in QThread::exec() () at /usr/lib/libQt5Core.so.5
#5  0x00007f53289aae75 in  () at /usr/lib/libQt5Qml.so.5
#6  0x00007f532de5bcf8 in  () at /usr/lib/libQt5Core.so.5
#7  0x00007f5329c50454 in start_thread () at /usr/lib/libpthread.so.0
#8  0x00007f53309e07df in clone () at /usr/lib/libc.so.6

Thread 3 (Thread 0x7f530ffff700 (LWP 9003)):
#0  0x00007f53309d7551 in ppoll () at /usr/lib/libc.so.6
#1  0x00007f532e0865f9 in qt_safe_poll(pollfd*, unsigned long, timespec const*) () at /usr/lib/libQt5Core.so.5
#2  0x00007f532e087efa in QEventDispatcherUNIX::processEvents(QFlags<QEventLoop::ProcessEventsFlag>) () at /usr/lib/libQt5Core.so.5
#3  0x00007f532e034d3a in QEventLoop::exec(QFlags<QEventLoop::ProcessEventsFlag>) () at /usr/lib/libQt5Core.so.5
#4  0x00007f532de57063 in QThread::exec() () at /usr/lib/libQt5Core.so.5
#5  0x00007f5327b74de5 in  () at /usr/lib/libQt5DBus.so.5
#6  0x00007f532de5bcf8 in  () at /usr/lib/libQt5Core.so.5
#7  0x00007f5329c50454 in start_thread () at /usr/lib/libpthread.so.0
#8  0x00007f53309e07df in clone () at /usr/lib/libc.so.6

Thread 2 (Thread 0x7f531684b700 (LWP 9001)):
#0  0x00007f53309d748d in poll () at /usr/lib/libc.so.6
#1  0x00007f532fb178e0 in  () at /usr/lib/libxcb.so.1
#2  0x00007f532fb19679 in xcb_wait_for_event () at /usr/lib/libxcb.so.1
#3  0x00007f53172f7789 in  () at /usr/lib/libQt5XcbQpa.so.5
#4  0x00007f532de5bcf8 in  () at /usr/lib/libQt5Core.so.5
#5  0x00007f5329c50454 in start_thread () at /usr/lib/libpthread.so.0
#6  0x00007f53309e07df in clone () at /usr/lib/libc.so.6

Thread 1 (Thread 0x7f5330f92840 (LWP 8998)):
[KCrash Handler]
#6  0x00007f53305a2a70 in KWin::EffectsHandlerImpl::setTabBoxWindow(KWin::EffectWindow*) () at /usr/lib/libkwin.so.5
#7  0x00007f532d32dc87 in  () at /usr/lib/libkwin4_effect_builtins.so.1
#8  0x00007f53305a9ae0 in KWin::EffectsHandlerImpl::checkInputWindowEvent(xcb_button_press_event_t*) () at /usr/lib/libkwin.so.5
#9  0x00007f5330510e1d in KWin::Workspace::workspaceEvent(xcb_generic_event_t*) () at /usr/lib/libkwin.so.5
#10 0x00007f532e033e7f in QAbstractEventDispatcher::filterNativeEvent(QByteArray const&, void*, long*) () at /usr/lib/libQt5Core.so.5
#11 0x00007f53172f8f54 in QXcbConnection::handleXcbEvent(xcb_generic_event_t*) () at /usr/lib/libQt5XcbQpa.so.5
#12 0x00007f53172f9c35 in QXcbConnection::processXcbEvents() () at /usr/lib/libQt5XcbQpa.so.5
#13 0x00007f532e062f29 in QObject::event(QEvent*) () at /usr/lib/libQt5Core.so.5
#14 0x00007f532ed1035c in QApplicationPrivate::notify_helper(QObject*, QEvent*) () at /usr/lib/libQt5Widgets.so.5
#15 0x00007f532ed17ad1 in QApplication::notify(QObject*, QEvent*) () at /usr/lib/libQt5Widgets.so.5
#16 0x00007f532e0368e0 in QCoreApplication::notifyInternal2(QObject*, QEvent*) () at /usr/lib/libQt5Core.so.5
#17 0x00007f532e03906d in QCoreApplicationPrivate::sendPostedEvents(QObject*, int, QThreadData*) () at /usr/lib/libQt5Core.so.5
#18 0x00007f532e087d27 in QEventDispatcherUNIX::processEvents(QFlags<QEventLoop::ProcessEventsFlag>) () at /usr/lib/libQt5Core.so.5
#19 0x00007f5317370ddd in  () at /usr/lib/libQt5XcbQpa.so.5
#20 0x00007f532e034d3a in QEventLoop::exec(QFlags<QEventLoop::ProcessEventsFlag>) () at /usr/lib/libQt5Core.so.5
#21 0x00007f532e03d23c in QCoreApplication::exec() () at /usr/lib/libQt5Core.so.5
#22 0x00007f5330c9f495 in kdemain () at /usr/lib/libkdeinit5_kwin_x11.so
#23 0x00007f5330918291 in __libc_start_main () at /usr/lib/libc.so.6
#24 0x000000000040069a in _start ()

Reported using DrKonqi