Application: systemsettings5 (5.2.2)

Qt Version: 5.4.1
Operating System: Linux 3.19.0-25-generic x86_64
Distribution: Ubuntu 15.04

-- Information about the crash:
I clicked "Display and monitor" icon and then entered "Compositor settings for desktop effects". I dropped down few menus just to see what options are possible but i have not changed any settings. When i tried to close the window, it crashed.

The crash can be reproduced sometimes.

-- Backtrace:
Application: Ustawienia systemowe (systemsettings5), signal: Segmentation fault
Using host libthread_db library "/lib/x86_64-linux-gnu/libthread_db.so.1".
[Current thread is 1 (Thread 0x7ff6ef228780 (LWP 2756))]

Thread 2 (Thread 0x7ff6df80f700 (LWP 2757)):
#0  0x00007ff6eb93b8dd in poll () at ../sysdeps/unix/syscall-template.S:81
#1  0x00007ff6e9c31b72 in _xcb_conn_wait (__timeout=-1, __nfds=1, __fds=0x7ff6df80ed40) at /usr/include/x86_64-linux-gnu/bits/poll2.h:46
#2  0x00007ff6e9c31b72 in _xcb_conn_wait (c=c@entry=0x24e4fa0, cond=cond@entry=0x24e4fe0, vector=vector@entry=0x0, count=count@entry=0x0) at ../../src/xcb_conn.c:447
#3  0x00007ff6e9c3364f in xcb_wait_for_event (c=0x24e4fa0) at ../../src/xcb_in.c:622
#4  0x00007ff6e25eb099 in QXcbEventReader::run() (this=0x24ef8e0) at qxcbconnection.cpp:1105
#5  0x00007ff6ebfc3b0e in QThreadPrivate::start(void*) (arg=0x24ef8e0) at thread/qthread_unix.cpp:337
#6  0x00007ff6e8b2f6aa in start_thread (arg=0x7ff6df80f700) at pthread_create.c:333
#7  0x00007ff6eb946eed in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:109

Thread 1 (Thread 0x7ff6ef228780 (LWP 2756)):
[KCrash Handler]
#6  0x00007ff6eaa44de0 in QQuickWindow::maybeUpdate() () at /usr/lib/x86_64-linux-gnu/libQt5Quick.so.5
#7  0x00007ff6eaa30e28 in QQuickItemPrivate::dirty(QQuickItemPrivate::DirtyType) () at /usr/lib/x86_64-linux-gnu/libQt5Quick.so.5
#8  0x00007ff6eaa3b045 in  () at /usr/lib/x86_64-linux-gnu/libQt5Quick.so.5
#9  0x00007ff6ec23373a in QObject::event(QEvent*) (this=0x3ca4100, e=<optimized out>) at kernel/qobject.cpp:1245
#10 0x00007ff6eaa39b6b in QQuickItem::event(QEvent*) () at /usr/lib/x86_64-linux-gnu/libQt5Quick.so.5
#11 0x00007ff6ecffbb2c in QApplicationPrivate::notify_helper(QObject*, QEvent*) (this=0x24d6e70, receiver=0x3ca4100, e=0x7ff6b0044eb0) at kernel/qapplication.cpp:3720
#12 0x00007ff6ed001000 in QApplication::notify(QObject*, QEvent*) (this=0x7ffc3db0c0c0, receiver=0x3ca4100, e=0x7ff6b0044eb0) at kernel/qapplication.cpp:3503
#13 0x00007ff6ec201c2b in QCoreApplication::notifyInternal(QObject*, QEvent*) (this=0x7ffc3db0c0c0, receiver=0x3ca4100, event=event@entry=0x7ff6b0044eb0) at kernel/qcoreapplication.cpp:935
#14 0x00007ff6ec203c9b in QCoreApplicationPrivate::sendPostedEvents(QObject*, int, QThreadData*) (event=0x7ff6b0044eb0, receiver=<optimized out>) at ../../include/QtCore/../../src/corelib/kernel/qcoreapplication.h:228
#15 0x00007ff6ec203c9b in QCoreApplicationPrivate::sendPostedEvents(QObject*, int, QThreadData*) (receiver=receiver@entry=0x0, event_type=event_type@entry=0, data=0x24d60c0) at kernel/qcoreapplication.cpp:1552
#16 0x00007ff6ec204298 in QCoreApplication::sendPostedEvents(QObject*, int) (receiver=receiver@entry=0x0, event_type=event_type@entry=0) at kernel/qcoreapplication.cpp:1410
#17 0x00007ff6ec25a843 in postEventSourceDispatch(GSource*, GSourceFunc, gpointer) (s=0x2516880) at kernel/qeventdispatcher_glib.cpp:271
#18 0x00007ff6e8609c3d in g_main_context_dispatch (context=0x7ff6d80016f0) at /build/buildd/glib2.0-2.44.1/./glib/gmain.c:3122
#19 0x00007ff6e8609c3d in g_main_context_dispatch (context=context@entry=0x7ff6d80016f0) at /build/buildd/glib2.0-2.44.1/./glib/gmain.c:3737
#20 0x00007ff6e8609f20 in g_main_context_iterate (context=context@entry=0x7ff6d80016f0, block=block@entry=1, dispatch=dispatch@entry=1, self=<optimized out>) at /build/buildd/glib2.0-2.44.1/./glib/gmain.c:3808
#21 0x00007ff6e8609fcc in g_main_context_iteration (context=0x7ff6d80016f0, may_block=1) at /build/buildd/glib2.0-2.44.1/./glib/gmain.c:3869
#22 0x00007ff6ec25ac57 in QEventDispatcherGlib::processEvents(QFlags<QEventLoop::ProcessEventsFlag>) (this=0x251b0e0, flags=...) at kernel/qeventdispatcher_glib.cpp:418
#23 0x00007ff6ec1ff3e2 in QEventLoop::exec(QFlags<QEventLoop::ProcessEventsFlag>) (this=this@entry=0x7ffc3db0bfa0, flags=..., flags@entry=...) at kernel/qeventloop.cpp:204
#24 0x00007ff6ec20702c in QCoreApplication::exec() () at kernel/qcoreapplication.cpp:1188
#25 0x00007ff6eca3331c in QGuiApplication::exec() () at kernel/qguiapplication.cpp:1510
#26 0x00007ff6ecff77a5 in QApplication::exec() () at kernel/qapplication.cpp:2956
#27 0x000000000040eebc in main(int, char**) (argc=1, argv=<optimized out>) at ../../app/main.cpp:54

Reported using DrKonqi