Application: systemsettings5 (5.3.2)

Qt Version: 5.4.1
Operating System: Linux 3.19.0-26-generic x86_64
Distribution: Ubuntu 15.04

-- Information about the crash:
I was switching between Composer and Screen (monitor) settings.
I is happend almost always when I do this switching.
System applet don't crash when I'm configuring Screen (monitor) settings, then I close system settings applet, reopen it, and then configure composer.

-- 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 0x7f6905647780 (LWP 4219))]

Thread 3 (Thread 0x7f69023d0700 (LWP 4220)):
#0  0x00007f69105758dd in poll () at ../sysdeps/unix/syscall-template.S:81
#1  0x00007f690e889b72 in  () at /usr/lib/x86_64-linux-gnu/libxcb.so.1
#2  0x00007f690e88b64f in xcb_wait_for_event () at /usr/lib/x86_64-linux-gnu/libxcb.so.1
#3  0x00007f69051bd099 in  () at /usr/lib/x86_64-linux-gnu/qt5/plugins/platforms/libqxcb.so
#4  0x00007f6910bf6b0e in  () at /usr/lib/x86_64-linux-gnu/libQt5Core.so.5
#5  0x00007f690d7a76aa in start_thread (arg=0x7f69023d0700) at pthread_create.c:333
#6  0x00007f6910580eed in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:109

Thread 2 (Thread 0x7f68f20cb700 (LWP 4253)):
#0  0x00007f690d2883fd in g_main_context_prepare (context=context@entry=0x7f68ec0009b0, priority=priority@entry=0x7f68f20cace0) at /build/buildd/glib2.0-2.44.1/./glib/gmain.c:3412
#1  0x00007f690d288de8 in g_main_context_iterate (context=context@entry=0x7f68ec0009b0, block=block@entry=1, dispatch=dispatch@entry=1, self=<optimized out>) at /build/buildd/glib2.0-2.44.1/./glib/gmain.c:3788
#2  0x00007f690d288fcc in g_main_context_iteration (context=0x7f68ec0009b0, may_block=1) at /build/buildd/glib2.0-2.44.1/./glib/gmain.c:3869
#3  0x00007f6910e8dc6c in QEventDispatcherGlib::processEvents(QFlags<QEventLoop::ProcessEventsFlag>) () at /usr/lib/x86_64-linux-gnu/libQt5Core.so.5
#4  0x00007f6910e323e2 in QEventLoop::exec(QFlags<QEventLoop::ProcessEventsFlag>) () at /usr/lib/x86_64-linux-gnu/libQt5Core.so.5
#5  0x00007f6910bf1b44 in QThread::exec() () at /usr/lib/x86_64-linux-gnu/libQt5Core.so.5
#6  0x00007f690fbbbf65 in  () at /usr/lib/x86_64-linux-gnu/libQt5Qml.so.5
#7  0x00007f6910bf6b0e in  () at /usr/lib/x86_64-linux-gnu/libQt5Core.so.5
#8  0x00007f690d7a76aa in start_thread (arg=0x7f68f20cb700) at pthread_create.c:333
#9  0x00007f6910580eed in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:109

Thread 1 (Thread 0x7f6905647780 (LWP 4219)):
[KCrash Handler]
#6  0x00007f690f67dd6b in QQuickItemPrivate::addToDirtyList() () at /usr/lib/x86_64-linux-gnu/libQt5Quick.so.5
#7  0x00007f690f67de28 in QQuickItemPrivate::dirty(QQuickItemPrivate::DirtyType) () at /usr/lib/x86_64-linux-gnu/libQt5Quick.so.5
#8  0x00007f690f688045 in  () at /usr/lib/x86_64-linux-gnu/libQt5Quick.so.5
#9  0x00007f6910e6673a in QObject::event(QEvent*) () at /usr/lib/x86_64-linux-gnu/libQt5Core.so.5
#10 0x00007f690f686b6b in QQuickItem::event(QEvent*) () at /usr/lib/x86_64-linux-gnu/libQt5Quick.so.5
#11 0x00007f6911c23b2c in QApplicationPrivate::notify_helper(QObject*, QEvent*) () at /usr/lib/x86_64-linux-gnu/libQt5Widgets.so.5
#12 0x00007f6911c29000 in QApplication::notify(QObject*, QEvent*) () at /usr/lib/x86_64-linux-gnu/libQt5Widgets.so.5
#13 0x00007f6910e34c2b in QCoreApplication::notifyInternal(QObject*, QEvent*) () at /usr/lib/x86_64-linux-gnu/libQt5Core.so.5
#14 0x00007f6910e36c9b in QCoreApplicationPrivate::sendPostedEvents(QObject*, int, QThreadData*) () at /usr/lib/x86_64-linux-gnu/libQt5Core.so.5
#15 0x00007f6910e8d843 in  () at /usr/lib/x86_64-linux-gnu/libQt5Core.so.5
#16 0x00007f690d288c3d in g_main_context_dispatch (context=0x7f68fc001710) at /build/buildd/glib2.0-2.44.1/./glib/gmain.c:3122
#17 0x00007f690d288c3d in g_main_context_dispatch (context=context@entry=0x7f68fc001710) at /build/buildd/glib2.0-2.44.1/./glib/gmain.c:3737
#18 0x00007f690d288f20 in g_main_context_iterate (context=context@entry=0x7f68fc001710, block=block@entry=1, dispatch=dispatch@entry=1, self=<optimized out>) at /build/buildd/glib2.0-2.44.1/./glib/gmain.c:3808
#19 0x00007f690d288fcc in g_main_context_iteration (context=0x7f68fc001710, may_block=1) at /build/buildd/glib2.0-2.44.1/./glib/gmain.c:3869
#20 0x00007f6910e8dc57 in QEventDispatcherGlib::processEvents(QFlags<QEventLoop::ProcessEventsFlag>) () at /usr/lib/x86_64-linux-gnu/libQt5Core.so.5
#21 0x00007f6910e323e2 in QEventLoop::exec(QFlags<QEventLoop::ProcessEventsFlag>) () at /usr/lib/x86_64-linux-gnu/libQt5Core.so.5
#22 0x00007f6910e3a02c in QCoreApplication::exec() () at /usr/lib/x86_64-linux-gnu/libQt5Core.so.5
#23 0x000000000040ef6b in main ()

Reported using DrKonqi