Right click on desktop, select Add Widget, select PlasmoBiff and click add 
widget - pouf! plasma crashes (but immediately restarts). Here's the backtrace. 
I had a bunch of stuff running (kmail, skype, amarok, konsole, OO.org) but was 
able to reproduce this with most stuff turned off.

Rev 830974 .

Cheers
M.

Application: Plasma Workspace (plasma), signal SIGSEGV
Using host libthread_db library "/lib/libthread_db.so.1".
[Thread debugging using libthread_db enabled]
[New Thread -1208830256 (LWP 873)]
[New Thread -1311274096 (LWP 878)]
[New Thread -1260979312 (LWP 877)]
[New Thread -1234207856 (LWP 876)]
[KCrash handler]
#6  0x0676db1b in KConfigGroup::config (this=0xbf8f2088)
    at /home/kde-devel/kde/src/kdelibs/kdecore/config/kconfiggroup.cpp:693
#7  0x001d97ba in Plasma::Applet::saveState (this=0x97ae280, 
    group=@0xbf8f2088)
    at /home/kde-devel/kde/src/kdebase/workspace/libs/plasma/applet.cpp:262
#8  0x002032f7 in Plasma::Containment::addApplet (this=0x9850fc0, 
    applet=0x97ae280, pos=@0xbf8f2110, delayInit=false)
    at /home/kde-devel/kde/src/kdebase/workspace/libs/plasma/containment.cpp:568
#9  0x00203679 in Plasma::ContainmentPrivate::addApplet (this=0x984e8c0, 
    name=@0xbf8f21d0, args=@0xbf8f21cc, appletGeometry=@0xbf8f21a8, id=0, 
    delayInit=false)
    at 
/home/kde-devel/kde/src/kdebase/workspace/libs/plasma/containment.cpp:1235
#10 0x002036c3 in Plasma::Containment::addApplet (this=0x9850fc0, 
    name=@0xbf8f21d0, args=@0xbf8f21cc, appletGeometry=@0xbf8f21a8)
    at /home/kde-devel/kde/src/kdebase/workspace/libs/plasma/containment.cpp:511
#11 0x001e0c94 in Plasma::AppletBrowserWidget::addApplet (this=0x9e2f7b8)
    at 
/home/kde-devel/kde/src/kdebase/workspace/libs/plasma/appletbrowser.cpp:244
#12 0x001e0d9c in Plasma::AppletBrowserWidget::qt_metacall (this=0x9e2f7b8, 
    _c=QMetaObject::InvokeMetaMethod, _id=0, _a=0xbf8f2264)
    at 
/home/kde-devel/kde/build/kdebase/workspace/libs/plasma/appletbrowser.moc:74
#13 0x0123be61 in QMetaObject::activate (sender=0x9819978, 
    from_signal_index=42, to_signal_index=42, argv=0x0)
    at kernel/qobject.cpp:3007
#14 0x0123c2e3 in QMetaObject::activate (sender=0x9819978, m=0x27653c4, 
    local_signal_index=7, argv=0x0) at kernel/qobject.cpp:3080
#15 0x025496fd in KDialog::applyClicked (this=0x9819978)
    at /home/kde-devel/kde/build/kdelibs/kdeui/kdialog.moc:235
#16 0x0254adbd in KDialog::slotButtonClicked (this=0x9819978, button=8)
    at /home/kde-devel/kde/src/kdelibs/kdeui/dialogs/kdialog.cpp:848
#17 0x0254d3d3 in KDialog::qt_metacall (this=0x9819978, 
    _c=QMetaObject::InvokeMetaMethod, _id=33, _a=0xbf8f244c)
    at /home/kde-devel/kde/build/kdelibs/kdeui/kdialog.moc:181
#18 0x001e0224 in Plasma::AppletBrowser::qt_metacall (this=0x9819978, 
    _c=QMetaObject::InvokeMetaMethod, _id=68, _a=0xbf8f244c)
    at 
/home/kde-devel/kde/build/kdebase/workspace/libs/plasma/appletbrowser.moc:122
#19 0x0123be61 in QMetaObject::activate (sender=0x9de7a90, 
    from_signal_index=4, to_signal_index=4, argv=0xbf8f244c)
    at kernel/qobject.cpp:3007
#20 0x0123c2e3 in QMetaObject::activate (sender=0x9de7a90, m=0x12d5ad8, 
    local_signal_index=0, argv=0xbf8f244c) at kernel/qobject.cpp:3080
#21 0x0124310c in QSignalMapper::mapped (this=0x9de7a90, _t1=8)
    at .moc/debug-shared/moc_qsignalmapper.cpp:93
#22 0x012431ef in QSignalMapper::map (this=0x9de7a90, sender=0x9e756b0)
    at kernel/qsignalmapper.cpp:277
#23 0x012432f0 in QSignalMapper::map (this=0x9de7a90)
    at kernel/qsignalmapper.cpp:268
#24 0x01243453 in QSignalMapper::qt_metacall (this=0x9de7a90, 
    _c=QMetaObject::InvokeMetaMethod, _id=4, _a=0xbf8f25bc)
    at .moc/debug-shared/moc_qsignalmapper.cpp:80
#25 0x0123be61 in QMetaObject::activate (sender=0x9e756b0, 
    from_signal_index=29, to_signal_index=30, argv=0xbf8f25bc)
    at kernel/qobject.cpp:3007
#26 0x0123c06a in QMetaObject::activate (sender=0x9e756b0, m=0x7974624, 
    from_local_signal_index=2, to_local_signal_index=3, argv=0xbf8f25bc)
    at kernel/qobject.cpp:3100
#27 0x07895960 in QAbstractButton::clicked (this=0x9e756b0, _t1=false)
    at .moc/debug-shared/moc_qabstractbutton.cpp:185
#28 0x075e2908 in QAbstractButtonPrivate::emitClicked (this=0x9e8db00)
    at widgets/qabstractbutton.cpp:543
#29 0x075e3b27 in QAbstractButtonPrivate::click (this=0x9e8db00)
    at widgets/qabstractbutton.cpp:536
#30 0x075e3dcc in QAbstractButton::mouseReleaseEvent (this=0x9e756b0, 
    e=0xbf8f2de4) at widgets/qabstractbutton.cpp:1112
#31 0x072bfa43 in QWidget::event (this=0x9e756b0, event=0xbf8f2de4)
    at kernel/qwidget.cpp:6927
#32 0x075e28a2 in QAbstractButton::event (this=0x9e756b0, e=0xbf8f2de4)
    at widgets/qabstractbutton.cpp:1074
#33 0x07697161 in QPushButton::event (this=0x9e756b0, e=0xbf8f2de4)
    at widgets/qpushbutton.cpp:658
#34 0x0725fd07 in QApplicationPrivate::notify_helper (this=0x9741d20, 
    receiver=0x9e756b0, e=0xbf8f2de4) at kernel/qapplication.cpp:3772
#35 0x0726088c in QApplication::notify (this=0x973bf48, receiver=0x9e756b0, 
    e=0xbf8f2de4) at kernel/qapplication.cpp:3501
#36 0x025e4639 in KApplication::notify (this=0x973bf48, receiver=0x9e756b0, 
    event=0xbf8f2de4)
    at /home/kde-devel/kde/src/kdelibs/kdeui/kernel/kapplication.cpp:311
#37 0x01227bb2 in QCoreApplication::notifyInternal (this=0x973bf48, 
    receiver=0x9e756b0, event=0xbf8f2de4) at kernel/qcoreapplication.cpp:583
#38 0x0726c165 in QCoreApplication::sendSpontaneousEvent (receiver=0x9e756b0, 
    event=0xbf8f2de4)
    at ../../include/QtCore/../../src/corelib/kernel/qcoreapplication.h:218
#39 0x07266cb6 in QApplicationPrivate::sendMouseEvent (receiver=0x9e756b0, 
    event=0xbf8f2de4, alienWidget=0x9e756b0, nativeWidget=0x9819978, 
    buttonDown=0x7982280, lastMouseReceiver=@0x7982284)
    at kernel/qapplication.cpp:2766
#40 0x072dbabe in QETWidget::translateMouseEvent (this=0x9819978, 
    event=0xbf8f3300) at kernel/qapplication_x11.cpp:4133
#41 0x072d9512 in QApplication::x11ProcessEvent (this=0x973bf48, 
    event=0xbf8f3300) at kernel/qapplication_x11.cpp:3133
#42 0x07308560 in x11EventSourceDispatch (s=0x9744d98, callback=0, 
    user_data=0x0) at kernel/qguieventdispatcher_glib.cpp:148
#43 0x037c01ac in g_main_context_dispatch () from /lib/libglib-2.0.so.0
#44 0x037c35ef in ?? () from /lib/libglib-2.0.so.0
#45 0x037c3b55 in g_main_context_iteration () from /lib/libglib-2.0.so.0
#46 0x01256be4 in QEventDispatcherGlib::processEvents (this=0x9740730, 
    flags=@0xbf8f34a8) at kernel/qeventdispatcher_glib.cpp:325
#47 0x07307db4 in QGuiEventDispatcherGlib::processEvents (this=0x9740730, 
    flags=@0xbf8f34d8) at kernel/qguieventdispatcher_glib.cpp:204
#48 0x0122470e in QEventLoop::processEvents (this=0xbf8f3550, 
    flags=@0xbf8f3514) at kernel/qeventloop.cpp:149
#49 0x0122494d in QEventLoop::exec (this=0xbf8f3550, flags=@0xbf8f3558)
    at kernel/qeventloop.cpp:196
#50 0x0122839b in QCoreApplication::exec () at kernel/qcoreapplication.cpp:845
#51 0x0725fa04 in QApplication::exec () at kernel/qapplication.cpp:3304
#52 0x001242e5 in kdemain (argc=1, argv=0xbf8f36f4)
    at /home/kde-devel/kde/src/kdebase/workspace/plasma/plasma/main.cpp:54
#53 0x08048806 in main (argc=1, argv=0x97a7760)
    at 
/home/kde-devel/kde/build/kdebase/workspace/plasma/plasma/plasma-qgv_dummy.cpp:3
#0  0x00110402 in __kernel_vsyscall ()