Ho aggiunto i repo factory e fatto l'aggiornamento a 4.2 rc1, tutto bene se non per questo problema con windows decorator:

Si è verificato un errore fatale
The application KDE Window Decorator (kde4-window-decorator) crashed and caused the signal 11 (SIGSEGV).
Please help us improve the software you use by filing a report at http://bugs.kde.org. Useful details include how to reproduce the error, documents that were loaded, etc.

Cliccando su mostra dettagli ho:

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Questo backtrace sembra essere inutile.
Probabilmente i pacchetti che stai utilizzando sono compilati in modo che non si possano creare dei backtrace corretti oppure lo stack frame è stato danneggiato seriamente durante il crash.

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0x00007ff11883ccb0 in nanosleep () from /lib64/libc.so.6
[Current thread is 1 (Thread 0x7ff11eb99790 (LWP 5346))]

Thread 1 (Thread 0x7ff11eb99790 (LWP 5346)):
#0 0x00007ff11883ccb0 in nanosleep () from /lib64/libc.so.6
#1 0x00007ff11883cadc in sleep () from /lib64/libc.so.6
#2 0x00007ff11841cd0f in ?? () from /usr/lib64/libkdeui.so.5
#3 0x00007ff11841d66a in KCrash::defaultCrashHandler(int) () from /usr/lib64/libkdeui.so.5
#4 <signal handler called>
#5 0x0000000000000000 in ?? ()
#6 0x00007ff10722b3e5 in ?? () from /usr/lib64/kde4/kwin3_oxygen.so
#7 0x00007ff119666b40 in KCommonDecoration::eventFilter(QObject*, QEvent*) () from /usr/lib64/libkdecorations.so.4
#8 0x00007ff11ab15358 in QCoreApplicationPrivate::sendThroughObjectEventFilters(QObject*, QEvent*) () from /usr/lib64/libQtCore.so.4
#9 0x00007ff11db2c18c in QApplicationPrivate::notify_helper(QObject*, QEvent*) () from /usr/lib64/libQtGui.so.4
#10 0x00007ff11db33f8a in QApplication::notify(QObject*, QEvent*) () from /usr/lib64/libQtGui.so.4
#11 0x00007ff1183baafb in KApplication::notify(QObject*, QEvent*) () from /usr/lib64/libkdeui.so.5
#12 0x00007ff11ab16091 in QCoreApplication::notifyInternal(QObject*, QEvent*) () from /usr/lib64/libQtCore.so.4
#13 0x00007ff11db79423 in QWidgetPrivate::sendPendingMoveAndResizeEvents(bool, bool) () from /usr/lib64/libQtGui.so.4
#14 0x00007ff11db81293 in QWidgetPrivate::show_helper() () from /usr/lib64/libQtGui.so.4
#15 0x00007ff11db818ea in QWidget::setVisible(bool) () from /usr/lib64/libQtGui.so.4
#16 0x00007ff11db816be in QWidgetPrivate::showChildren(bool) () from /usr/lib64/libQtGui.so.4
#17 0x00007ff11db812af in QWidgetPrivate::show_helper() () from /usr/lib64/libQtGui.so.4
#18 0x00007ff11db818ea in QWidget::setVisible(bool) () from /usr/lib64/libQtGui.so.4
#19 0x0000000000417258 in KWD::Window::resizeDecoration(bool) ()
#20 0x000000000041c700 in KWD::Window::Window(unsigned long, unsigned long, unsigned long, KWD::Window::Type, int, int, int, int) ()
#21 0x0000000000414198 in KWD::Decorator::enableDecorations(unsigned long, int) ()
#22 0x000000000040c80a in main ()

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Cosa puo' essere e come si puo' risolvere??

Grazie e a presto