Application: plasma-desktop (4.11.13)
KDE Platform Version: 4.14.2
Qt Version: 4.8.6
Operating System: Linux 3.14-2-amd64 x86_64
Distribution: Debian GNU/Linux 8.0 (jessie)

-- Information about the crash:
- What I was doing when the application crashed: testing the activity bar, when used directly from desltop it worked perfetly, but when I dragged it to bottom panel and testing it, plasma crashes.

- Default settings, no custom settings.

The crash can be reproduced every time.

-- Backtrace:
Application: Plasma Desktop Shell (plasma-desktop), signal: Segmentation fault
Using host libthread_db library "/lib/x86_64-linux-gnu/libthread_db.so.1".
[Current thread is 1 (Thread 0x7ff40f425800 (LWP 1401))]

Thread 3 (Thread 0x7ff3e3c96700 (LWP 1402)):
#0  pthread_cond_wait@@GLIBC_2.3.2 () at ../nptl/sysdeps/unix/sysv/linux/x86_64/pthread_cond_wait.S:185
#1  0x00007ff407e30dea in ?? () from /usr/lib/x86_64-linux-gnu/libQtScript.so.4
#2  0x00007ff407e30e19 in ?? () from /usr/lib/x86_64-linux-gnu/libQtScript.so.4
#3  0x00007ff40265e0a4 in start_thread (arg=0x7ff3e3c96700) at pthread_create.c:309
#4  0x00007ff40ed2a04d in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:111

Thread 2 (Thread 0x7ff35d740700 (LWP 1403)):
#0  0x00007ff40ed2150d in poll () at ../sysdeps/unix/syscall-template.S:81
#1  0x00007ff401d3aee4 in ?? () from /lib/x86_64-linux-gnu/libglib-2.0.so.0
#2  0x00007ff401d3affc in g_main_context_iteration () from /lib/x86_64-linux-gnu/libglib-2.0.so.0
#3  0x00007ff40b7e5d37 in QEventDispatcherGlib::processEvents(QFlags<QEventLoop::ProcessEventsFlag>) () from /usr/lib/x86_64-linux-gnu/libQtCore.so.4
#4  0x00007ff40b7b5271 in QEventLoop::processEvents(QFlags<QEventLoop::ProcessEventsFlag>) () from /usr/lib/x86_64-linux-gnu/libQtCore.so.4
#5  0x00007ff40b7b55d5 in QEventLoop::exec(QFlags<QEventLoop::ProcessEventsFlag>) () from /usr/lib/x86_64-linux-gnu/libQtCore.so.4
#6  0x00007ff40b6a9e99 in QThread::exec() () from /usr/lib/x86_64-linux-gnu/libQtCore.so.4
#7  0x00007ff40b795ac3 in ?? () from /usr/lib/x86_64-linux-gnu/libQtCore.so.4
#8  0x00007ff40b6ac70f in ?? () from /usr/lib/x86_64-linux-gnu/libQtCore.so.4
#9  0x00007ff40265e0a4 in start_thread (arg=0x7ff35d740700) at pthread_create.c:309
#10 0x00007ff40ed2a04d in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:111

Thread 1 (Thread 0x7ff40f425800 (LWP 1401)):
[KCrash Handler]
#6  0x000000000463f430 in ?? ()
#7  0x00007ff3ec04bb6b in GroupingContainment::sceneEventFilter(QGraphicsItem*, QEvent*) () from /usr/lib/libplasma_groupingcontainment.so.4
#8  0x00007ff40b1158ac in ?? () from /usr/lib/x86_64-linux-gnu/libQtGui.so.4
#9  0x00007ff40b115941 in ?? () from /usr/lib/x86_64-linux-gnu/libQtGui.so.4
#10 0x00007ff40b11faf1 in ?? () from /usr/lib/x86_64-linux-gnu/libQtGui.so.4
#11 0x00007ff40b11fe72 in ?? () from /usr/lib/x86_64-linux-gnu/libQtGui.so.4
#12 0x00007ff40b12033a in QGraphicsScene::mouseMoveEvent(QGraphicsSceneMouseEvent*) () from /usr/lib/x86_64-linux-gnu/libQtGui.so.4
#13 0x00007ff40b12d2ef in QGraphicsScene::event(QEvent*) () from /usr/lib/x86_64-linux-gnu/libQtGui.so.4
#14 0x00007ff40ab0748c in QApplicationPrivate::notify_helper(QObject*, QEvent*) () from /usr/lib/x86_64-linux-gnu/libQtGui.so.4
#15 0x00007ff40ab0dfa8 in QApplication::notify(QObject*, QEvent*) () from /usr/lib/x86_64-linux-gnu/libQtGui.so.4
#16 0x00007ff40c4da1aa in KApplication::notify(QObject*, QEvent*) () from /usr/lib/libkdeui.so.5
#17 0x00007ff40b7b671d in QCoreApplication::notifyInternal(QObject*, QEvent*) () from /usr/lib/x86_64-linux-gnu/libQtCore.so.4
#18 0x00007ff40b143638 in QGraphicsViewPrivate::mouseMoveEventHandler(QMouseEvent*) () from /usr/lib/x86_64-linux-gnu/libQtGui.so.4
#19 0x00007ff40b1446ca in QGraphicsView::mouseMoveEvent(QMouseEvent*) () from /usr/lib/x86_64-linux-gnu/libQtGui.so.4
#20 0x00007ff40ab5a748 in QWidget::event(QEvent*) () from /usr/lib/x86_64-linux-gnu/libQtGui.so.4
#21 0x00007ff40af1c83e in QFrame::event(QEvent*) () from /usr/lib/x86_64-linux-gnu/libQtGui.so.4
#22 0x00007ff40b145e81 in QGraphicsView::viewportEvent(QEvent*) () from /usr/lib/x86_64-linux-gnu/libQtGui.so.4
#23 0x00007ff40b7b6886 in QCoreApplicationPrivate::sendThroughObjectEventFilters(QObject*, QEvent*) () from /usr/lib/x86_64-linux-gnu/libQtCore.so.4
#24 0x00007ff40ab0746c in QApplicationPrivate::notify_helper(QObject*, QEvent*) () from /usr/lib/x86_64-linux-gnu/libQtGui.so.4
#25 0x00007ff40ab0e10f in QApplication::notify(QObject*, QEvent*) () from /usr/lib/x86_64-linux-gnu/libQtGui.so.4
#26 0x00007ff40c4da1aa in KApplication::notify(QObject*, QEvent*) () from /usr/lib/libkdeui.so.5
#27 0x00007ff40b7b671d in QCoreApplication::notifyInternal(QObject*, QEvent*) () from /usr/lib/x86_64-linux-gnu/libQtCore.so.4
#28 0x00007ff40ab0d76f in QApplicationPrivate::sendMouseEvent(QWidget*, QMouseEvent*, QWidget*, QWidget*, QWidget**, QPointer<QWidget>&, bool) () from /usr/lib/x86_64-linux-gnu/libQtGui.so.4
#29 0x00007ff40ab84432 in ?? () from /usr/lib/x86_64-linux-gnu/libQtGui.so.4
#30 0x00007ff40ab82e2c in QApplication::x11ProcessEvent(_XEvent*) () from /usr/lib/x86_64-linux-gnu/libQtGui.so.4
#31 0x00007ff40ababed2 in ?? () from /usr/lib/x86_64-linux-gnu/libQtGui.so.4
#32 0x00007ff401d3ac5d in g_main_context_dispatch () from /lib/x86_64-linux-gnu/libglib-2.0.so.0
#33 0x00007ff401d3af48 in ?? () from /lib/x86_64-linux-gnu/libglib-2.0.so.0
#34 0x00007ff401d3affc in g_main_context_iteration () from /lib/x86_64-linux-gnu/libglib-2.0.so.0
#35 0x00007ff40b7e5d1d in QEventDispatcherGlib::processEvents(QFlags<QEventLoop::ProcessEventsFlag>) () from /usr/lib/x86_64-linux-gnu/libQtCore.so.4
#36 0x00007ff40ababf96 in ?? () from /usr/lib/x86_64-linux-gnu/libQtGui.so.4
#37 0x00007ff40b7b5271 in QEventLoop::processEvents(QFlags<QEventLoop::ProcessEventsFlag>) () from /usr/lib/x86_64-linux-gnu/libQtCore.so.4
#38 0x00007ff40b7b55d5 in QEventLoop::exec(QFlags<QEventLoop::ProcessEventsFlag>) () from /usr/lib/x86_64-linux-gnu/libQtCore.so.4
#39 0x00007ff40b7bb059 in QCoreApplication::exec() () from /usr/lib/x86_64-linux-gnu/libQtCore.so.4
#40 0x00007ff40f02d4bd in kdemain () from /usr/lib/kde4/libkdeinit/libkdeinit4_plasma-desktop.so
#41 0x00007ff40ec65b45 in __libc_start_main (main=0x4006f0, argc=1, argv=0x7fffaf3a8c28, init=<optimized out>, fini=<optimized out>, rtld_fini=<optimized out>, stack_end=0x7fffaf3a8c18) at libc-start.c:287
#42 0x000000000040071e in _start ()

Reported using DrKonqi