Application: kwin_x11 (5.2.2)
 (Compiled from sources)
Qt Version: 5.4.1
Operating System: Linux 3.16.0-31-generic x86_64
Distribution: Ubuntu 15.04

-- Information about the crash:
- What I was doing when the application crashed:
It's enough to login in Kubuntu 15.04. I installed kubunbtu ppa/backports before.

- Unusual behavior I noticed:
crash of kwin_x11. There are no frames around the applications. You can't close them ...

The crash can be reproduced every time.

-- Backtrace:
Application: KWin (kwin_x11), signal: Segmentation fault
Using host libthread_db library "/lib/x86_64-linux-gnu/libthread_db.so.1".
[KCrash Handler]
#6  0x0000000000000000 in ?? ()
#7  0x00007fbfd690b181 in KDecoration2::DecoratedClient::color(KDecoration2::ColorGroup, KDecoration2::ColorRole) const () from /usr/lib/x86_64-linux-gnu/libkdecorations2.so.5
#8  0x00007fbfbdafc349 in ?? () from /usr/lib/x86_64-linux-gnu/qt5/plugins/org.kde.kdecoration2/breezedecoration.so
#9  0x00007fbfbdb042ba in ?? () from /usr/lib/x86_64-linux-gnu/qt5/plugins/org.kde.kdecoration2/breezedecoration.so
#10 0x00007fbfda7dc721 in KWin::Decoration::DecorationBridge::createDecoration (this=0xd94cf0, client=0xf22be0) at ../decorations/decorationbridge.cpp:215
#11 0x00007fbfda6e01c9 in KWin::Client::createDecoration (this=this@entry=0xf22be0, oldgeom=...) at ../client.cpp:515
#12 0x00007fbfda6e05db in KWin::Client::updateDecoration (this=this@entry=0xf22be0, check_workspace_pos=check_workspace_pos@entry=false, force=force@entry=false) at ../client.cpp:502
#13 0x00007fbfda71a900 in KWin::Client::manage (this=this@entry=0xf22be0, w=w@entry=197132293, isMapped=isMapped@entry=true) at ../manage.cpp:375
#14 0x00007fbfda6cc31d in KWin::Workspace::createClient (this=0xd87070, this@entry=0x7fbfda6ea9d0 <KWin::GlobalShortcutsManager::objectDeleted(QObject*)>, w=197132293, is_mapped=is_mapped@entry=true) at ../workspace.cpp:462
#15 0x00007fbfda6cfa5d in KWin::Workspace::init (this=this@entry=0xd87070) at ../workspace.cpp:348
#16 0x00007fbfda6d058f in KWin::Workspace::Workspace (this=0xd87070, restore=<optimized out>) at ../workspace.cpp:228
#17 0x00007fbfdae75aa6 in operator() (__closure=<synthetic pointer>) at ../main_x11.cpp:170
#18 call (arg=<optimized out>, f=...) at /usr/include/x86_64-linux-gnu/qt5/QtCore/qobjectdefs_impl.h:494
#19 call<QtPrivate::List<>, void> (arg=<optimized out>, f=...) at /usr/include/x86_64-linux-gnu/qt5/QtCore/qobjectdefs_impl.h:551
#20 QtPrivate::QFunctorSlotObject<KWin::ApplicationX11::performStartup()::<lambda()>, 0, QtPrivate::List<>, void>::impl(int, QtPrivate::QSlotObjectBase *, QObject *, void **, bool *) (which=<optimized out>, this_=<optimized out>, r=<optimized out>, a=<optimized out>, ret=<optimized out>) at /usr/include/x86_64-linux-gnu/qt5/QtCore/qobject_impl.h:192
#21 0x00007fbfd93cb35a in call (a=0x7fffe9647920, r=0xd0c500, this=0xd0c2d0) at ../../include/QtCore/../../src/corelib/kernel/qobject_impl.h:124
#22 QMetaObject::activate (sender=0xd0c500, signalOffset=<optimized out>, local_signal_index=local_signal_index@entry=1, argv=argv@entry=0x0) at kernel/qobject.cpp:3702
#23 0x00007fbfd93cc057 in QMetaObject::activate (sender=<optimized out>, m=m@entry=0x7fbfda440bc0 <KSelectionOwner::staticMetaObject>, local_signal_index=local_signal_index@entry=1, argv=argv@entry=0x0) at kernel/qobject.cpp:3582
#24 0x00007fbfda2300e3 in KSelectionOwner::claimedOwnership (this=<optimized out>) at moc_kselectionowner.cpp:150
#25 0x00007fbfda213a9b in KSelectionOwner::Private::claimSucceeded (this=0xd16ce0) at ../../src/kselectionowner.cpp:206
#26 0x00007fbfda214221 in KSelectionOwner::filterEvent (this=0xd0c500, ev_P=<optimized out>) at ../../src/kselectionowner.cpp:424
#27 0x00007fbfd9397510 in QAbstractEventDispatcher::filterNativeEvent (this=this@entry=0xce6c30, eventType=..., message=message@entry=0x7fbfc00012f0, result=result@entry=0x7fffe9647ab8) at kernel/qabstracteventdispatcher.cpp:460
#28 0x00007fbfc5df302d in QXcbConnection::handleXcbEvent (this=this@entry=0xcb18e0, event=event@entry=0x7fbfc00012f0) at qxcbconnection.cpp:863
#29 0x00007fbfc5df44bb in QXcbConnection::processXcbEvents (this=0xcb18e0) at qxcbconnection.cpp:1303
#30 0x00007fbfd93cc73a in QObject::event (this=0xcb18e0, e=<optimized out>) at kernel/qobject.cpp:1245
#31 0x00007fbfd9ca4b2c in QApplicationPrivate::notify_helper (this=0xcaa920, receiver=0xcb18e0, e=0x7fbfc0001340) at kernel/qapplication.cpp:3720
#32 0x00007fbfd9caa000 in QApplication::notify (this=0x7fffe96481a0, receiver=0xcb18e0, e=0x7fbfc0001340) at kernel/qapplication.cpp:3503
#33 0x00007fbfd939ac2b in QCoreApplication::notifyInternal (this=0x7fffe96481a0, receiver=0xcb18e0, event=event@entry=0x7fbfc0001340) at kernel/qcoreapplication.cpp:935
#34 0x00007fbfd939cc9b in sendEvent (event=0x7fbfc0001340, receiver=<optimized out>) at ../../include/QtCore/../../src/corelib/kernel/qcoreapplication.h:228
#35 QCoreApplicationPrivate::sendPostedEvents (receiver=receiver@entry=0x0, event_type=event_type@entry=0, data=0xc9b2f0) at kernel/qcoreapplication.cpp:1552
#36 0x00007fbfd93f1112 in QEventDispatcherUNIX::processEvents (this=0xce6c30, flags=flags@entry=...) at kernel/qeventdispatcher_unix.cpp:579
#37 0x00007fbfc5e4a96d in QUnixEventDispatcherQPA::processEvents (this=<optimized out>, flags=...) at eventdispatchers/qunixeventdispatcher.cpp:62
#38 0x00007fbfd93983e2 in QEventLoop::exec (this=this@entry=0x7fffe96480c0, flags=..., flags@entry=...) at kernel/qeventloop.cpp:204
#39 0x00007fbfd93a002c in QCoreApplication::exec () at kernel/qcoreapplication.cpp:1188
#40 0x00007fbfd96df31c in QGuiApplication::exec () at kernel/qguiapplication.cpp:1510
#41 0x00007fbfd9ca07a5 in QApplication::exec () at kernel/qapplication.cpp:2956
#42 0x00007fbfdae768c3 in kdemain (argc=3, argv=0x7fffe96482f8) at ../main_x11.cpp:294
#43 0x00007fbfdaac8a40 in __libc_start_main (main=0x400790 <main(int, char**)>, argc=3, argv=0x7fffe96482f8, init=<optimized out>, fini=<optimized out>, rtld_fini=<optimized out>, stack_end=0x7fffe96482e8) at libc-start.c:289
#44 0x00000000004007c9 in _start ()

Reported using DrKonqi