Application: plasma-desktop (4.11.17)
KDE Platform Version: 4.14.6
Qt Version: 4.8.6
Operating System: Linux 3.16.7-7-desktop x86_64
Distribution: "openSUSE 13.2 (Harlequin) (x86_64)"

-- Information about the crash:
just move cursor to an icon (maybe need to click on expanding item) and after preview was shown palsma crashes  sometimes

plasma theme - full flat fixed
decoration -qtcurve
panel on the top with Kickoff, Desktop pager, Smooth tasks, clock
nvidia 340.76 x64
Smooth tasks: expand on attention, on hover; tooltip smooth, new
desktop effects/taskbar thumbnails is on

The crash can be reproduced sometimes.

-- Backtrace:
Application: Plasma Desktop Shell (plasma-desktop), signal: Segmentation fault
Using host libthread_db library "/lib64/libthread_db.so.1".
[Current thread is 1 (Thread 0x7f1fd0fb6780 (LWP 22063))]

Thread 3 (Thread 0x7f1fa3ec5700 (LWP 22068)):
#0  0x00007f1fcf87405f in pthread_cond_wait@@GLIBC_2.3.2 () from /lib64/libpthread.so.0
#1  0x00007f1fc21038cb in ?? () from /usr/lib64/libQtScript.so.4
#2  0x00007f1fc2103909 in ?? () from /usr/lib64/libQtScript.so.4
#3  0x00007f1fcf8700a4 in start_thread () from /lib64/libpthread.so.0
#4  0x00007f1fce5dd06d in clone () from /lib64/libc.so.6

Thread 2 (Thread 0x7f1f9af27700 (LWP 22069)):
#0  0x00007f1fd0fedbb6 in ?? ()
#1  0x7fffffff00000000 in ?? ()
#2  0xcfc3526000000000 in ?? ()
#3  0x10002ee000007f1f in ?? ()
#4  0x9af26c6800007f1f in ?? ()
#5  0x9af26c0000007f1f in ?? ()
#6  0x7fffffff00007f1f in ?? ()
#7  0xcfc3500000000000 in ?? ()
#8  0x9af26c7000007f1f in ?? ()
#9  0xce5e9cad00007f1f in ?? ()
#10 0x0000000900007f1f in ?? ()
#11 0xcfb5ad4700000000 in ?? ()
#12 0xbd777ce000007f1f in ?? ()
#13 0xbe9797db00007f1f in ?? ()
#14 0x000263ed00007f1f in ?? ()
#15 0x100008c000000000 in ?? ()
#16 0x9af26c2000007f1f in ?? ()
#17 0xcfc3687500007f1f in ?? ()
#18 0xffffffff00007f1f in ?? ()
#19 0x9af26c64ffffffff in ?? ()
#20 0x9af26c7000007f1f in ?? ()
#21 0x9af26c6800007f1f in ?? ()
#22 0x0000000000007f1f in ?? ()
#23 0xcfc34f8c00000000 in ?? ()
#24 0x0000000000007f1f in ?? ()
#25 0x0000000000000000 in ?? ()

Thread 1 (Thread 0x7f1fd0fb6780 (LWP 22063)):
[KCrash Handler]
#5  0x00007f1fa6565910 in TaskManager::TaskItem::task() const () from /usr/lib64/libtaskmanager.so.4
#6  0x00007f1fa5ea60ce in SmoothTasks::Task::task (this=<optimized out>) at /usr/src/debug/smooth-tasks-fork-531/applet/SmoothTasks/Task.cpp:196
#7  0x00007f1fa5eb2c97 in SmoothTasks::WindowPreview::leftClickTask (this=0x4e76be0) at /usr/src/debug/smooth-tasks-fork-531/applet/SmoothTasks/WindowPreview.cpp:333
#8  0x00007f1fa5eb2d8d in SmoothTasks::WindowPreview::mouseReleaseEvent (this=0x4e76be0, event=0x7fff223fbc40) at /usr/src/debug/smooth-tasks-fork-531/applet/SmoothTasks/WindowPreview.cpp:508
#9  0x00007f1fcedd3c0a in QWidget::event(QEvent*) () from /usr/lib64/libQtGui.so.4
#10 0x00007f1fced8476c in QApplicationPrivate::notify_helper(QObject*, QEvent*) () from /usr/lib64/libQtGui.so.4
#11 0x00007f1fced8adea in QApplication::notify(QObject*, QEvent*) () from /usr/lib64/libQtGui.so.4
#12 0x00007f1fd09abcea in KApplication::notify(QObject*, QEvent*) () from /usr/lib64/libkdeui.so.5
#13 0x00007f1fcfc082ad in QCoreApplication::notifyInternal(QObject*, QEvent*) () from /usr/lib64/libQtCore.so.4
#14 0x00007f1fced8a5e3 in QApplicationPrivate::sendMouseEvent(QWidget*, QMouseEvent*, QWidget*, QWidget*, QWidget**, QPointer<QWidget>&, bool) () from /usr/lib64/libQtGui.so.4
#15 0x00007f1fcedfbc9b in ?? () from /usr/lib64/libQtGui.so.4
#16 0x00007f1fcedfa70c in QApplication::x11ProcessEvent(_XEvent*) () from /usr/lib64/libQtGui.so.4
#17 0x00007f1fcee215c2 in ?? () from /usr/lib64/libQtGui.so.4
#18 0x00007f1fcb6e7a04 in g_main_context_dispatch () from /usr/lib64/libglib-2.0.so.0
#19 0x00007f1fcb6e7c48 in ?? () from /usr/lib64/libglib-2.0.so.0
#20 0x00007f1fcb6e7cec in g_main_context_iteration () from /usr/lib64/libglib-2.0.so.0
#21 0x00007f1fcfc350be in QEventDispatcherGlib::processEvents(QFlags<QEventLoop::ProcessEventsFlag>) () from /usr/lib64/libQtCore.so.4
#22 0x00007f1fcee21676 in ?? () from /usr/lib64/libQtGui.so.4
#23 0x00007f1fcfc06e6f in QEventLoop::processEvents(QFlags<QEventLoop::ProcessEventsFlag>) () from /usr/lib64/libQtCore.so.4
#24 0x00007f1fcfc07165 in QEventLoop::exec(QFlags<QEventLoop::ProcessEventsFlag>) () from /usr/lib64/libQtCore.so.4
#25 0x00007f1fcfc0c5b9 in QCoreApplication::exec() () from /usr/lib64/libQtCore.so.4
#26 0x00007f1fb8d61b94 in kdemain () from /usr/lib64/libkdeinit4_plasma-desktop.so
#27 0x0000000000408815 in _start ()

Reported using DrKonqi