Created attachment 61525 [details]
Taskbar with wrong window position

Version:           unspecified (using Devel) 
OS:                Linux

Taskbar changes position of window on it (see attachment «Taskbar with wrong window position»), or even garbages (att-t «Garbage at taskbar»).

If I try to do anything (for example, change the settings of taskbar, or add launcher on it) — plasma chashes with useless backtrace:

Application: Оболочка Plasma (kdeinit4), signal: Segmentation fault
[Current thread is 1 (Thread 0xb57eeb60 (LWP 700))]

Thread 6 (Thread 0xaba51b70 (LWP 704)):
#0  0xb5bcb898 in g_main_context_check () from /usr/lib/libglib-2.0.so.0
#1  0xb5bcc310 in ?? () from /usr/lib/libglib-2.0.so.0
#2  0xb5bcc6da in g_main_context_iteration () from /usr/lib/libglib-2.0.so.0
#3  0xb6ef14a7 in QEventDispatcherGlib::processEvents(QFlags<QEventLoop::ProcessEventsFlag>) () from /usr/lib/libQtCore.so.4
#4  0xb6ec21fd in QEventLoop::processEvents(QFlags<QEventLoop::ProcessEventsFlag>) () from /usr/lib/libQtCore.so.4
#5  0xb6ec2441 in QEventLoop::exec(QFlags<QEventLoop::ProcessEventsFlag>) () from /usr/lib/libQtCore.so.4
#6  0xb6dc5abb in QThread::exec() () from /usr/lib/libQtCore.so.4
#7  0xb6ea2d9d in ?? () from /usr/lib/libQtCore.so.4
#8  0xb6dc8913 in ?? () from /usr/lib/libQtCore.so.4
#9  0xb6d52c77 in start_thread () from /lib/libpthread.so.0
#10 0xb614343e in clone () from /lib/libc.so.6

Thread 5 (Thread 0xaa128b70 (LWP 9856)):
#0  0xb7856424 in __kernel_vsyscall ()
#1  0xb6d5687b in pthread_cond_wait@@GLIBC_2.3.2 () from /lib/libpthread.so.0
#2  0xb6dc8e20 in QWaitCondition::wait(QMutex*, unsigned long) () from /usr/lib/libQtCore.so.4
#3  0xb31a8916 in ?? () from /usr/lib/libthreadweaver.so.4
#4  0xb31ab3fb in ?? () from /usr/lib/libthreadweaver.so.4
#5  0xb31a854a in ?? () from /usr/lib/libthreadweaver.so.4
#6  0xb31ab4fc in ?? () from /usr/lib/libthreadweaver.so.4
#7  0xb31a84a3 in ?? () from /usr/lib/libthreadweaver.so.4
#8  0xb31aa034 in ?? () from /usr/lib/libthreadweaver.so.4
#9  0xb31aa0ea in ThreadWeaver::Thread::run() () from /usr/lib/libthreadweaver.so.4
#10 0xb6dc8913 in ?? () from /usr/lib/libQtCore.so.4
#11 0xb6d52c77 in start_thread () from /lib/libpthread.so.0
#12 0xb614343e in clone () from /lib/libc.so.6

Thread 4 (Thread 0xab13bb70 (LWP 9857)):
#0  0xb7856424 in __kernel_vsyscall ()
#1  0xb6d5687b in pthread_cond_wait@@GLIBC_2.3.2 () from /lib/libpthread.so.0
#2  0xb6dc8e20 in QWaitCondition::wait(QMutex*, unsigned long) () from /usr/lib/libQtCore.so.4
#3  0xb31a8916 in ?? () from /usr/lib/libthreadweaver.so.4
#4  0xb31ab3fb in ?? () from /usr/lib/libthreadweaver.so.4
#5  0xb31a854a in ?? () from /usr/lib/libthreadweaver.so.4
#6  0xb31ab4fc in ?? () from /usr/lib/libthreadweaver.so.4
#7  0xb31a84a3 in ?? () from /usr/lib/libthreadweaver.so.4
#8  0xb31aa034 in ?? () from /usr/lib/libthreadweaver.so.4
#9  0xb31aa0ea in ThreadWeaver::Thread::run() () from /usr/lib/libthreadweaver.so.4
#10 0xb6dc8913 in ?? () from /usr/lib/libQtCore.so.4
#11 0xb6d52c77 in start_thread () from /lib/libpthread.so.0
#12 0xb614343e in clone () from /lib/libc.so.6

Thread 3 (Thread 0xa84a1b70 (LWP 9858)):
#0  0xb7856424 in __kernel_vsyscall ()
#1  0xb6d5687b in pthread_cond_wait@@GLIBC_2.3.2 () from /lib/libpthread.so.0
#2  0xb6dc8e20 in QWaitCondition::wait(QMutex*, unsigned long) () from /usr/lib/libQtCore.so.4
#3  0xb31a8916 in ?? () from /usr/lib/libthreadweaver.so.4
#4  0xb31ab3fb in ?? () from /usr/lib/libthreadweaver.so.4
#5  0xb31a854a in ?? () from /usr/lib/libthreadweaver.so.4
#6  0xb31ab4fc in ?? () from /usr/lib/libthreadweaver.so.4
#7  0xb31a84a3 in ?? () from /usr/lib/libthreadweaver.so.4
#8  0xb31ab518 in ?? () from /usr/lib/libthreadweaver.so.4
#9  0xb31a84a3 in ?? () from /usr/lib/libthreadweaver.so.4
#10 0xb31ab518 in ?? () from /usr/lib/libthreadweaver.so.4
#11 0xb31a84a3 in ?? () from /usr/lib/libthreadweaver.so.4
#12 0xb31ab518 in ?? () from /usr/lib/libthreadweaver.so.4
#13 0xb31a84a3 in ?? () from /usr/lib/libthreadweaver.so.4
#14 0xb31aa034 in ?? () from /usr/lib/libthreadweaver.so.4
#15 0xb31aa0ea in ThreadWeaver::Thread::run() () from /usr/lib/libthreadweaver.so.4
#16 0xb6dc8913 in ?? () from /usr/lib/libQtCore.so.4
#17 0xb6d52c77 in start_thread () from /lib/libpthread.so.0
#18 0xb614343e in clone () from /lib/libc.so.6

Thread 2 (Thread 0xa7ca0b70 (LWP 9859)):
#0  0xb7856424 in __kernel_vsyscall ()
#1  0xb6d5687b in pthread_cond_wait@@GLIBC_2.3.2 () from /lib/libpthread.so.0
#2  0xb6dc8e20 in QWaitCondition::wait(QMutex*, unsigned long) () from /usr/lib/libQtCore.so.4
#3  0xb31a8916 in ?? () from /usr/lib/libthreadweaver.so.4
#4  0xb31ab3fb in ?? () from /usr/lib/libthreadweaver.so.4
#5  0xb31a854a in ?? () from /usr/lib/libthreadweaver.so.4
#6  0xb31ab4fc in ?? () from /usr/lib/libthreadweaver.so.4
#7  0xb31a84a3 in ?? () from /usr/lib/libthreadweaver.so.4
#8  0xb31ab518 in ?? () from /usr/lib/libthreadweaver.so.4
#9  0xb31a84a3 in ?? () from /usr/lib/libthreadweaver.so.4
#10 0xb31ab518 in ?? () from /usr/lib/libthreadweaver.so.4
#11 0xb31a84a3 in ?? () from /usr/lib/libthreadweaver.so.4
#12 0xb31ab518 in ?? () from /usr/lib/libthreadweaver.so.4
#13 0xb31a84a3 in ?? () from /usr/lib/libthreadweaver.so.4
#14 0xb31ab518 in ?? () from /usr/lib/libthreadweaver.so.4
#15 0xb31a84a3 in ?? () from /usr/lib/libthreadweaver.so.4
#16 0xb31aa034 in ?? () from /usr/lib/libthreadweaver.so.4
#17 0xb31aa0ea in ThreadWeaver::Thread::run() () from /usr/lib/libthreadweaver.so.4
#18 0xb6dc8913 in ?? () from /usr/lib/libQtCore.so.4
#19 0xb6d52c77 in start_thread () from /lib/libpthread.so.0
#20 0xb614343e in clone () from /lib/libc.so.6

Thread 1 (Thread 0xb57eeb60 (LWP 700)):
[KCrash Handler]
#7  0xb11af6be in TaskManager::Task::classClass() const () from /usr/lib/libtaskmanager.so.4
#8  0xb1192f9b in TaskManager::LauncherItem::associateItemIfMatches(TaskManager::AbstractGroupableItem*) () from /usr/lib/libtaskmanager.so.4
#9  0xb118e41c in TaskManager::GroupManager::addLauncher(KUrl const&, QIcon, QString, QString) () from /usr/lib/libtaskmanager.so.4
#10 0xb11678c0 in ?? () from /usr/lib/kde4/plasma_applet_tasks.so
#11 0xb6a4b5a7 in QGraphicsItem::sceneEvent(QEvent*) () from /usr/lib/libQtGui.so.4
#12 0xb6aa8746 in QGraphicsWidget::sceneEvent(QEvent*) () from /usr/lib/libQtGui.so.4
#13 0xb6a74b1e in ?? () from /usr/lib/libQtGui.so.4
#14 0xb6a763df in ?? () from /usr/lib/libQtGui.so.4
#15 0xb6a76429 in QGraphicsScene::dropEvent(QGraphicsSceneDragDropEvent*) () from /usr/lib/libQtGui.so.4
#16 0xb6a848bc in QGraphicsScene::event(QEvent*) () from /usr/lib/libQtGui.so.4
#17 0xb63f4084 in QApplicationPrivate::notify_helper(QObject*, QEvent*) () from /usr/lib/libQtGui.so.4
#18 0xb63f9433 in QApplication::notify(QObject*, QEvent*) () from /usr/lib/libQtGui.so.4
#19 0xb75df8a1 in KApplication::notify(QObject*, QEvent*) () from /usr/lib/libkdeui.so.5
#20 0xb6ec31be in QCoreApplication::notifyInternal(QObject*, QEvent*) () from /usr/lib/libQtCore.so.4
#21 0xb6a9d6b6 in QGraphicsView::dropEvent(QDropEvent*) () from /usr/lib/libQtGui.so.4
#22 0xb25aef3a in ?? () from /usr/lib/libkdeinit4_plasma-desktop.so
#23 0xb644e77f in QWidget::event(QEvent*) () from /usr/lib/libQtGui.so.4
#24 0xb6849d95 in QFrame::event(QEvent*) () from /usr/lib/libQtGui.so.4
#25 0xb68dba31 in QAbstractScrollArea::viewportEvent(QEvent*) () from /usr/lib/libQtGui.so.4
#26 0xb6aa6c04 in QGraphicsView::viewportEvent(QEvent*) () from /usr/lib/libQtGui.so.4
#27 0xb68de136 in ?? () from /usr/lib/libQtGui.so.4
#28 0xb6ec3356 in QCoreApplicationPrivate::sendThroughObjectEventFilters(QObject*, QEvent*) () from /usr/lib/libQtCore.so.4
#29 0xb63f4052 in QApplicationPrivate::notify_helper(QObject*, QEvent*) () from /usr/lib/libQtGui.so.4
#30 0xb63f9dec in QApplication::notify(QObject*, QEvent*) () from /usr/lib/libQtGui.so.4
#31 0xb75df8a1 in KApplication::notify(QObject*, QEvent*) () from /usr/lib/libkdeui.so.5
#32 0xb6ec31be in QCoreApplication::notifyInternal(QObject*, QEvent*) () from /usr/lib/libQtCore.so.4
#33 0xb64897dc in ?? () from /usr/lib/libQtGui.so.4
#34 0xb648a924 in ?? () from /usr/lib/libQtGui.so.4
#35 0xb648d6a2 in ?? () from /usr/lib/libQtGui.so.4
#36 0xb6ec328b in QCoreApplicationPrivate::sendThroughApplicationEventFilters(QObject*, QEvent*) () from /usr/lib/libQtCore.so.4
#37 0xb63f3ffa in QApplicationPrivate::notify_helper(QObject*, QEvent*) () from /usr/lib/libQtGui.so.4
#38 0xb63fa0f0 in QApplication::notify(QObject*, QEvent*) () from /usr/lib/libQtGui.so.4
#39 0xb75df8a1 in KApplication::notify(QObject*, QEvent*) () from /usr/lib/libkdeui.so.5
#40 0xb6ec31be in QCoreApplication::notifyInternal(QObject*, QEvent*) () from /usr/lib/libQtCore.so.4
#41 0xb63f5045 in QApplicationPrivate::sendMouseEvent(QWidget*, QMouseEvent*, QWidget*, QWidget*, QWidget**, QPointer<QWidget>&, bool) () from /usr/lib/libQtGui.so.4
#42 0xb647e677 in ?? () from /usr/lib/libQtGui.so.4
#43 0xb647d20d in QApplication::x11ProcessEvent(_XEvent*) () from /usr/lib/libQtGui.so.4
#44 0xb64a7aac in ?? () from /usr/lib/libQtGui.so.4
#45 0xb5bcbc4f in g_main_context_dispatch () from /usr/lib/libglib-2.0.so.0
#46 0xb5bcc3b0 in ?? () from /usr/lib/libglib-2.0.so.0
#47 0xb5bcc6da in g_main_context_iteration () from /usr/lib/libglib-2.0.so.0
#48 0xb6ef144a in QEventDispatcherGlib::processEvents(QFlags<QEventLoop::ProcessEventsFlag>) () from /usr/lib/libQtCore.so.4
#49 0xb64a76ba in ?? () from /usr/lib/libQtGui.so.4
#50 0xb6ec21fd in QEventLoop::processEvents(QFlags<QEventLoop::ProcessEventsFlag>) () from /usr/lib/libQtCore.so.4
#51 0xb6ec2441 in QEventLoop::exec(QFlags<QEventLoop::ProcessEventsFlag>) () from /usr/lib/libQtCore.so.4
#52 0xb648d38b in ?? () from /usr/lib/libQtGui.so.4
#53 0xb6407761 in QDrag::exec(QFlags<Qt::DropAction>, Qt::DropAction) () from /usr/lib/libQtGui.so.4
#54 0xb6407805 in QDrag::exec(QFlags<Qt::DropAction>) () from /usr/lib/libQtGui.so.4
#55 0xb12c0d28 in ?? () from /usr/lib/kde4/plasma_applet_launcher.so
#56 0xb6986cfd in QAbstractItemView::mouseMoveEvent(QMouseEvent*) () from /usr/lib/libQtGui.so.4
#57 0xb12bee1b in ?? () from /usr/lib/kde4/plasma_applet_launcher.so
#58 0xb644e014 in QWidget::event(QEvent*) () from /usr/lib/libQtGui.so.4
#59 0xb6849d95 in QFrame::event(QEvent*) () from /usr/lib/libQtGui.so.4
#60 0xb68dba31 in QAbstractScrollArea::viewportEvent(QEvent*) () from /usr/lib/libQtGui.so.4
#61 0xb697d7cc in QAbstractItemView::viewportEvent(QEvent*) () from /usr/lib/libQtGui.so.4
#62 0xb68de136 in ?? () from /usr/lib/libQtGui.so.4
#63 0xb6ec3356 in QCoreApplicationPrivate::sendThroughObjectEventFilters(QObject*, QEvent*) () from /usr/lib/libQtCore.so.4
#64 0xb63f4052 in QApplicationPrivate::notify_helper(QObject*, QEvent*) () from /usr/lib/libQtGui.so.4
#65 0xb63fa0f0 in QApplication::notify(QObject*, QEvent*) () from /usr/lib/libQtGui.so.4
#66 0xb75df8a1 in KApplication::notify(QObject*, QEvent*) () from /usr/lib/libkdeui.so.5
#67 0xb6ec31be in QCoreApplication::notifyInternal(QObject*, QEvent*) () from /usr/lib/libQtCore.so.4
#68 0xb63f5045 in QApplicationPrivate::sendMouseEvent(QWidget*, QMouseEvent*, QWidget*, QWidget*, QWidget**, QPointer<QWidget>&, bool) () from /usr/lib/libQtGui.so.4
#69 0xb647e677 in ?? () from /usr/lib/libQtGui.so.4
#70 0xb647d20d in QApplication::x11ProcessEvent(_XEvent*) () from /usr/lib/libQtGui.so.4
#71 0xb64a7aac in ?? () from /usr/lib/libQtGui.so.4
#72 0xb5bcbc4f in g_main_context_dispatch () from /usr/lib/libglib-2.0.so.0
#73 0xb5bcc3b0 in ?? () from /usr/lib/libglib-2.0.so.0
#74 0xb5bcc6da in g_main_context_iteration () from /usr/lib/libglib-2.0.so.0
#75 0xb6ef144a in QEventDispatcherGlib::processEvents(QFlags<QEventLoop::ProcessEventsFlag>) () from /usr/lib/libQtCore.so.4
#76 0xb64a76ba in ?? () from /usr/lib/libQtGui.so.4
#77 0xb6ec21fd in QEventLoop::processEvents(QFlags<QEventLoop::ProcessEventsFlag>) () from /usr/lib/libQtCore.so.4
#78 0xb6ec2441 in QEventLoop::exec(QFlags<QEventLoop::ProcessEventsFlag>) () from /usr/lib/libQtCore.so.4
#79 0xb6ec6bad in QCoreApplication::exec() () from /usr/lib/libQtCore.so.4
#80 0xb63f1ed4 in QApplication::exec() () from /usr/lib/libQtGui.so.4
#81 0xb25a8fcb in kdemain () from /usr/lib/libkdeinit4_plasma-desktop.so
#82 0x0804f2b2 in _start ()

Plasma restarts after crash and taskbar looks fine.

Reproducible: Sometimes

Steps to Reproduce:
I haven't good use-case to reproduce it. I noticed that this bug happens often with java windows (some webstart applets for example).

Actual Results:  
Wrong taskbar appearance, plasma crash.

Expected Results:  
// Why this field is required?

Qt: 4.7.3
KDE: 4.6.90 (4.7 RC1)