Version:            (using KDE Devel)
Installed from:    Compiled sources
OS:                Linux

When I do the following, plasma crashes:

1) Right click on desktop
2) Klick on "Add Widgets"
3) Add SlideInSlideOutExample twice
4) Remove SlideInSlideOutExample widget by klicking "x" in "add widgets manager"

Note: After the first crash, plasma recovers, but after the second crash, it does not, and the desktop stays empty (no widgets at all)

Plasma crashes with the following backtrace:

Using host libthread_db library "/lib/tls/i686/cmov/libthread_db.so.1".
[Thread debugging using libthread_db enabled]
[New Thread -1238616368 (LWP 3815)]
[New Thread -1293206640 (LWP 3839)]
[New Thread -1265615984 (LWP 3816)]
[KCrash handler]
#6  0xb6c10294 in q_atomic_increment ()
   from /storage/tmp/kde4dev/qt-unstable/lib/libQtGui.so.4
#7  0xb6c102d3 in QBasicAtomic::ref ()
   from /storage/tmp/kde4dev/qt-unstable/lib/libQtGui.so.4
#8  0xb717e5d3 in QList<QGraphicsItem*>::QList ()
   from /storage/tmp/kde4dev/qt-unstable/lib/libQtGui.so.4
#9  0xb716f715 in QGraphicsItem::children ()
   from /storage/tmp/kde4dev/qt-unstable/lib/libQtGui.so.4
#10 0xb7173f54 in qt_graphicsItem_fullUpdate ()
   from /storage/tmp/kde4dev/qt-unstable/lib/libQtGui.so.4
#11 0xb7174120 in QGraphicsItem::setPos ()
   from /storage/tmp/kde4dev/qt-unstable/lib/libQtGui.so.4
#12 0xb7e8dd61 in QGraphicsItem::setPos (this=0x89d5208, ax=0, ay=100)
    at /storage/tmp/kde4dev/qt-unstable/include/QtGui/qgraphicsitem.h:331
#13 0xb7e8d9da in Plasma::Animator::slideOut (this=0x8137738, 
    progress=0.80000000000000004, item=0x89d5208, start=@0x8786f5c, 
    destination=@0x8786f64)
    at /storage/tmp/kde4dev/kdebase/workspace/libs/plasma/animator.cpp:124
#14 0xb7ed7b4f in Plasma::Phase::Private::performMovement (this=0x8126fb8, 
    amount=0.80000000000000004, state=0x8786f40)
    at /storage/tmp/kde4dev/kdebase/workspace/libs/plasma/phase.cpp:152
#15 0xb7ed5b87 in Plasma::Phase::timerEvent (this=0x8127590, event=0xbfba6914)
    at /storage/tmp/kde4dev/kdebase/workspace/libs/plasma/phase.cpp:479
#16 0xb744c812 in QObject::event ()
   from /storage/tmp/kde4dev/qt-unstable/lib/libQtCore.so.4
#17 0xb6c13ce1 in QApplicationPrivate::notify_helper ()
   from /storage/tmp/kde4dev/qt-unstable/lib/libQtGui.so.4
#18 0xb6c13fe2 in QApplication::notify ()
   from /storage/tmp/kde4dev/qt-unstable/lib/libQtGui.so.4
#19 0xb79c5a8b in KApplication::notify (this=0x8060950, receiver=0x8127590, 
    event=0xbfba6914)
    at /storage/tmp/kde4dev/kdelibs/kdeui/kernel/kapplication.cpp:319
#20 0xb743a41e in QCoreApplication::notifyInternal ()
   from /storage/tmp/kde4dev/qt-unstable/lib/libQtCore.so.4
#21 0xb743d7ed in QCoreApplication::sendEvent ()
   from /storage/tmp/kde4dev/qt-unstable/lib/libQtCore.so.4
#22 0xb7466b65 in QTimerInfoList::activateTimers ()
   from /storage/tmp/kde4dev/qt-unstable/lib/libQtCore.so.4
#23 0xb7463ab4 in timerSourceDispatch ()
   from /storage/tmp/kde4dev/qt-unstable/lib/libQtCore.so.4
#24 0xb6476df2 in g_main_context_dispatch () from /usr/lib/libglib-2.0.so.0
#25 0xb6479dcf in ?? () from /usr/lib/libglib-2.0.so.0
#26 0x0807c698 in ?? ()
#27 0x00000000 in ?? ()
#0  0xffffe402 in __kernel_vsyscall ()