Application that crashed: plasmoidviewer
Version of the application: 1.0
KDE Version: 4.2.95 (KDE 4.2.95 (KDE 4.3 RC1))
Qt Version: 4.5.0
Operating System: Linux 2.6.28-13-generic i686
Distribution: Ubuntu 9.04

What I was doing when the application crashed:
this python code in a plasmoid applet crashes plasma:

widget = QGraphicsWidget()
label = Plasma.Label(widget)
extender = Plasma.Extender(self.applet)
item = Plasma.ExtenderItem(extender)
item.setWidget(widget)

note: self.extender() won't work in python applets, it gives an exception:

    self.extender()                                                     
RuntimeError: no access to protected functions or signals for objects not created from Python

 -- Backtrace:
Application: Plasma Widget Viewer (plasmoidviewer), signal: Segmentation fault
[KCrash Handler]
#6  0xb7a43ae2 in ?? () from /usr/lib/libplasma.so.3
#7  0xb7a43d0e in Plasma::ExtenderItem::~ExtenderItem () from /usr/lib/libplasma.so.3
#8  0xa8be3152 in sipPlasma_ExtenderItem::~sipPlasma_ExtenderItem () from /usr/lib/python2.6/dist-packages/PyKDE4/plasma.so
#9  0xb76c5478 in QGraphicsItem::~QGraphicsItem () from /usr/lib/libQtGui.so.4
#10 0xb7709a82 in QGraphicsWidget::~QGraphicsWidget () from /usr/lib/libQtGui.so.4
#11 0xb7a3d471 in Plasma::Extender::~Extender () from /usr/lib/libplasma.so.3
#12 0xa8be18e2 in sipPlasma_Extender::~sipPlasma_Extender () from /usr/lib/python2.6/dist-packages/PyKDE4/plasma.so
#13 0xa8bc3f30 in ?? () from /usr/lib/python2.6/dist-packages/PyKDE4/plasma.so
#14 0xa8bc3f87 in ?? () from /usr/lib/python2.6/dist-packages/PyKDE4/plasma.so
#15 0xa9c515a3 in ?? () from /usr/lib/python2.6/dist-packages/sip.so
#16 0xa959a6cf in ?? () from /usr/lib/libpython2.6.so.1.0
#17 0xa9567edf in ?? () from /usr/lib/libpython2.6.so.1.0
#18 0xa95e3691 in PyEval_EvalCodeEx () from /usr/lib/libpython2.6.so.1.0
#19 0xa956987a in ?? () from /usr/lib/libpython2.6.so.1.0
#20 0xa953998c in PyObject_Call () from /usr/lib/libpython2.6.so.1.0
#21 0xa954a7a8 in ?? () from /usr/lib/libpython2.6.so.1.0
#22 0xa953998c in PyObject_Call () from /usr/lib/libpython2.6.so.1.0
#23 0xa95dba34 in PyEval_CallObjectWithKeywords () from /usr/lib/libpython2.6.so.1.0
#24 0xa9c56ca7 in sip_api_invoke_slot () from /usr/lib/python2.6/dist-packages/sip.so
#25 0xa9374021 in ?? () from /usr/lib/python2.6/dist-packages/PyQt4/QtCore.so
#26 0xa9374c07 in ?? () from /usr/lib/python2.6/dist-packages/PyQt4/QtCore.so
#27 0xa9374cae in ?? () from /usr/lib/python2.6/dist-packages/PyQt4/QtCore.so
#28 0xb6bbaca8 in QMetaObject::activate () from /usr/lib/libQtCore.so.4
#29 0xb6bbb932 in QMetaObject::activate () from /usr/lib/libQtCore.so.4
#30 0xb7aaeef7 in Plasma::PushButton::clicked () from /usr/lib/libplasma.so.3
#31 0xb7ab073d in Plasma::PushButton::qt_metacall () from /usr/lib/libplasma.so.3
#32 0xa8b5ebe2 in sipPlasma_PushButton::qt_metacall () from /usr/lib/python2.6/dist-packages/PyKDE4/plasma.so
#33 0xb6bbaca8 in QMetaObject::activate () from /usr/lib/libQtCore.so.4
#34 0xb6bbb0e0 in QMetaObject::activate () from /usr/lib/libQtCore.so.4
#35 0xb773a2b1 in QAbstractButton::clicked () from /usr/lib/libQtGui.so.4
#36 0xb74650b9 in ?? () from /usr/lib/libQtGui.so.4
#37 0xb7466d14 in ?? () from /usr/lib/libQtGui.so.4
#38 0xb7466fa6 in QAbstractButton::mouseReleaseEvent () from /usr/lib/libQtGui.so.4
#39 0xb70dab43 in QWidget::event () from /usr/lib/libQtGui.so.4
#40 0xb7464f5e in QAbstractButton::event () from /usr/lib/libQtGui.so.4
#41 0xb750ff20 in QPushButton::event () from /usr/lib/libQtGui.so.4
#42 0xb7083e9c in QApplicationPrivate::notify_helper () from /usr/lib/libQtGui.so.4
#43 0xb708cb11 in QApplication::notify () from /usr/lib/libQtGui.so.4
#44 0xb7d323dd in KApplication::notify () from /usr/lib/libkdeui.so.5
#45 0xb6ba4a3b in QCoreApplication::notifyInternal () from /usr/lib/libQtCore.so.4
#46 0xb708bb7e in QApplicationPrivate::sendMouseEvent () from /usr/lib/libQtGui.so.4
#47 0xb771aef1 in ?? () from /usr/lib/libQtGui.so.4
#48 0xa8b309af in sipPlasma_PushButton::mouseReleaseEvent () from /usr/lib/python2.6/dist-packages/PyKDE4/plasma.so
#49 0xb76b9c54 in QGraphicsItem::sceneEvent () from /usr/lib/libQtGui.so.4
#50 0xb7706f9f in QGraphicsWidget::sceneEvent () from /usr/lib/libQtGui.so.4
#51 0xa8b423bf in sipPlasma_PushButton::sceneEvent () from /usr/lib/python2.6/dist-packages/PyKDE4/plasma.so
#52 0xb76de1cc in ?? () from /usr/lib/libQtGui.so.4
#53 0xb76df412 in ?? () from /usr/lib/libQtGui.so.4
#54 0xb76e71c1 in QGraphicsScene::mouseReleaseEvent () from /usr/lib/libQtGui.so.4
#55 0xb76e754a in QGraphicsScene::event () from /usr/lib/libQtGui.so.4
#56 0xb7083e9c in QApplicationPrivate::notify_helper () from /usr/lib/libQtGui.so.4
#57 0xb708c19e in QApplication::notify () from /usr/lib/libQtGui.so.4
#58 0xb7d323dd in KApplication::notify () from /usr/lib/libkdeui.so.5
#59 0xb6ba4a3b in QCoreApplication::notifyInternal () from /usr/lib/libQtCore.so.4
#60 0xb76fc7c2 in QGraphicsView::mouseReleaseEvent () from /usr/lib/libQtGui.so.4
#61 0xb70dab43 in QWidget::event () from /usr/lib/libQtGui.so.4
#62 0xb74b4993 in QFrame::event () from /usr/lib/libQtGui.so.4
#63 0xb755494f in QAbstractScrollArea::viewportEvent () from /usr/lib/libQtGui.so.4
#64 0xb76f8102 in QGraphicsView::viewportEvent () from /usr/lib/libQtGui.so.4
#65 0xb7556f55 in ?? () from /usr/lib/libQtGui.so.4
#66 0xb6ba3c5a in QCoreApplicationPrivate::sendThroughObjectEventFilters () from /usr/lib/libQtCore.so.4
#67 0xb7083e7a in QApplicationPrivate::notify_helper () from /usr/lib/libQtGui.so.4
#68 0xb708cb11 in QApplication::notify () from /usr/lib/libQtGui.so.4
#69 0xb7d323dd in KApplication::notify () from /usr/lib/libkdeui.so.5
#70 0xb6ba4a3b in QCoreApplication::notifyInternal () from /usr/lib/libQtCore.so.4
#71 0xb708bb7e in QApplicationPrivate::sendMouseEvent () from /usr/lib/libQtGui.so.4
#72 0xb70fb97e in ?? () from /usr/lib/libQtGui.so.4
#73 0xb70faca7 in QApplication::x11ProcessEvent () from /usr/lib/libQtGui.so.4
#74 0xb7125c6a in ?? () from /usr/lib/libQtGui.so.4
#75 0xb4ffab88 in IA__g_main_context_dispatch (context=0x8afd298) at /build/buildd/glib2.0-2.20.1/glib/gmain.c:1814
#76 0xb4ffe0eb in g_main_context_iterate (context=0x8afd298, block=1, dispatch=1, self=0x8afb0a0) at /build/buildd/glib2.0-2.20.1/glib/gmain.c:2448
#77 0xb4ffe268 in IA__g_main_context_iteration (context=0x8afd298, may_block=1) at /build/buildd/glib2.0-2.20.1/glib/gmain.c:2511
#78 0xb6bd0438 in QEventDispatcherGlib::processEvents () from /usr/lib/libQtCore.so.4
#79 0xb7125365 in ?? () from /usr/lib/libQtGui.so.4
#80 0xb6ba306a in QEventLoop::processEvents () from /usr/lib/libQtCore.so.4
#81 0xb6ba34aa in QEventLoop::exec () from /usr/lib/libQtCore.so.4
#82 0xb6ba5959 in QCoreApplication::exec () from /usr/lib/libQtCore.so.4
#83 0xb7083d17 in QApplication::exec () from /usr/lib/libQtGui.so.4
#84 0x0804fa21 in _start ()

Reported using DrKonqi