Version:           unspecified (using KDE 4.7.0) 
OS:                Linux

When using Aurorae decorations, kwin sometimes crashes on switching group tabs when a window has been removed from the very same group before. Also, when clicking a tab that has not been switched to before altering the group, the decoration flickers (text is being rendered as if there was one more window in the group). Additionally, kwin only restarts without compositing, although the bug occurs independently from compositing state.

Reproducible: Sometimes

Steps to Reproduce:
1. Select an aurorae theme with centered title alignment (see below)
2. Create a group of ~6 or 7 windows
3. Activate each tab at least once
4. Remove one of the windows
5. Try to activate each tab
6. See kwin crash.

Actual Results:  
KWin crashes with the following backtrace:

Application: KWin (kwin), signal: Segmentation fault
[Current thread is 1 (Thread 0x7f6b2549f7a0 (LWP 22525))]
 
Thread 2 (Thread 0x7f6b0c47b700 (LWP 22539)):
#0  0x00007f6b20c80ac4 in pthread_cond_wait@@GLIBC_2.3.2 () from /lib/libpthread.so.0
#1  0x00007f6b23b302e2 in ?? () from /usr/lib/libQtScript.so.4
#2  0x00007f6b23b30319 in ?? () from /usr/lib/libQtScript.so.4
#3  0x00007f6b225319e3 in ?? () from /usr/lib/libGL.so.1
#4  0x00007f6b20c7cd60 in start_thread () from /lib/libpthread.so.0
#5  0x00007f6b24d1ae2d in clone () from /lib/libc.so.6
#6  0x0000000000000000 in ?? ()
 
Thread 1 (Thread 0x7f6b2549f7a0 (LWP 22525)):
[KCrash Handler]
#6  0x000000000000000f in ?? ()
#7  0x00007f6b241c21a5 in Plasma::Corona::popupPosition(QGraphicsItem const*, QSize const&, Qt::AlignmentFlag) () from /usr/lib/libplasma.so.3
#8  0x00007f6b2426fc10 in ?? () from /usr/lib/libplasma.so.3
#9  0x00007f6b2426fee5 in Plasma::ToolTipManager::qt_metacall(QMetaObject::Call, int, void**) () from /usr/lib/libplasma.so.3
#10 0x00007f6b20fff7fa in QMetaObject::activate(QObject*, QMetaObject const*, int, void**) () from /usr/lib/libQtCore.so.4
#11 0x00007f6b210030c9 in QObject::event(QEvent*) () from /usr/lib/libQtCore.so.4
#12 0x00007f6b201ad174 in QApplicationPrivate::notify_helper(QObject*, QEvent*) () from /usr/lib/libQtGui.so.4
#13 0x00007f6b201b1fe1 in QApplication::notify(QObject*, QEvent*) () from /usr/lib/libQtGui.so.4
#14 0x00007f6b24812226 in KApplication::notify(QObject*, QEvent*) () from /usr/lib/libkdeui.so.5
#15 0x00007f6b20fecbbc in QCoreApplication::notifyInternal(QObject*, QEvent*) () from /usr/lib/libQtCore.so.4
#16 0x00007f6b21019732 in ?? () from /usr/lib/libQtCore.so.4
#17 0x00007f6b2101a1cb in QEventDispatcherUNIX::processEvents(QFlags<QEventLoop::ProcessEventsFlag>) () from /usr/lib/libQtCore.so.4
#18 0x00007f6b20250fde in ?? () from /usr/lib/libQtGui.so.4
#19 0x00007f6b20febdb2 in QEventLoop::processEvents(QFlags<QEventLoop::ProcessEventsFlag>) () from /usr/lib/libQtCore.so.4
#20 0x00007f6b20febfb7 in QEventLoop::exec(QFlags<QEventLoop::ProcessEventsFlag>) () from /usr/lib/libQtCore.so.4
#21 0x00007f6b20ff01ab in QCoreApplication::exec() () from /usr/lib/libQtCore.so.4
#22 0x00007f6b25003416 in kdemain () from /usr/lib/libkdeinit4_kwin.so
#23 0x00007f6b24c6817d in __libc_start_main () from /lib/libc.so.6
#24 0x00000000004005f1 in _start ()

Expected Results:  
KWin should *not* crash.

I've tried multiple Aurorae themes and it seems it only happens with themes that use centered title caption.