Version:            (using Devel)
OS:                Linux
Installed from:    Compiled sources

I am using KDE 4.1.85
Folderview had a very similar bug, bug 178102

To reproduce:

-Add a Now Playing plasmoid to the desktop
-Drag it by its applet handle to the panel

Plasma then crashes with the following backtrace:

Application: Plasma Workspace (plasma), signal SIGSEGV
[Current thread is 0 (LWP 19589)]

Thread 3 (Thread 0xa9464b90 (LWP 19590)):
#0  0xb8004424 in __kernel_vsyscall ()
#1  0xb583d075 in pthread_cond_wait@@GLIBC_2.3.2 () from /lib/tls/i686/cmov/libpthread.so.0
#2  0xb64389ed in pthread_cond_wait () from /lib/tls/i686/cmov/libc.so.6
#3  0xb66236f2 in QWaitCondition::wait (this=0x8d11f50, mutex=0x8d11f4c, time=4294967295) at thread/qwaitcondition_unix.cpp:82
#4  0xb799e532 in QHostInfoAgent::run (this=0x8d11f40) at kernel/qhostinfo.cpp:241
#5  0xb66226ae in QThreadPrivate::start (arg=0x8d11f40) at thread/qthread_unix.cpp:185
#6  0xb583950f in start_thread () from /lib/tls/i686/cmov/libpthread.so.0
#7  0xb642a7ee in clone () from /lib/tls/i686/cmov/libc.so.6

Thread 2 (Thread 0xa8c30b90 (LWP 19591)):
#0  0xb8004424 in __kernel_vsyscall ()
#1  0xb583d075 in pthread_cond_wait@@GLIBC_2.3.2 () from /lib/tls/i686/cmov/libpthread.so.0
#2  0xb64389ed in pthread_cond_wait () from /lib/tls/i686/cmov/libc.so.6
#3  0xb66236f2 in QWaitCondition::wait (this=0x87732a0, mutex=0x877329c, time=4294967295) at thread/qwaitcondition_unix.cpp:82
#4  0xa970a392 in RenderThread::run (this=0x8773294) at /build/buildd/kdebase-workspace-4.1.85/plasma/wallpapers/image/renderthread.cpp:91
#5  0xb66226ae in QThreadPrivate::start (arg=0x8773294) at thread/qthread_unix.cpp:185
#6  0xb583950f in start_thread () from /lib/tls/i686/cmov/libpthread.so.0
#7  0xb642a7ee in clone () from /lib/tls/i686/cmov/libc.so.6

Thread 1 (Thread 0xb4b41b20 (LWP 19589)):
[KCrash Handler]
#6  0x00000011 in ?? ()
#7  0xa83ff873 in NowPlaying::constraintsEvent (this=0x8fd0720, constraints={i = -1077913740}) at /build/buildd/kdeplasma-addons-4.1.85/applets/nowplaying/nowplaying.cpp:187
#8  0xb7e1e858 in Plasma::Applet::flushPendingConstraintsEvents () from /usr/lib/libplasma.so.3
#9  0xb7e1f0e8 in Plasma::Applet::timerEvent () from /usr/lib/libplasma.so.3
#10 0xb672253f in QObject::event (this=0x8fd0720, e=0xbfc05cac) at kernel/qobject.cpp:1120
#11 0xb6fa7447 in QGraphicsWidget::event (this=0x8fd0720, event=0xbfc05cac) at graphicsview/qgraphicswidget.cpp:1239
#12 0xb69e78ec in QApplicationPrivate::notify_helper (this=0x8649fa8, receiver=0x8fd0720, e=0xbfc05cac) at kernel/qapplication.cpp:3803
#13 0xb69ef72e in QApplication::notify (this=0x8632e20, receiver=0x8fd0720, e=0xbfc05cac) at kernel/qapplication.cpp:3393
#14 0xb7764d3d in KApplication::notify (this=0x8632e20, receiver=0x8fd0720, event=0xbfc05cac) at /build/buildd/kde4libs-4.1.85/kdeui/kernel/kapplication.cpp:307
#15 0xb6712e61 in QCoreApplication::notifyInternal (this=0x8632e20, receiver=0x8fd0720, event=0xbfc05cac) at kernel/qcoreapplication.cpp:587
#16 0xb6740d81 in QTimerInfoList::activateTimers (this=0x864cb4c) at ../../include/QtCore/../../src/corelib/kernel/qcoreapplication.h:209
#17 0xb673d520 in timerSourceDispatch (source=0x864cb18) at kernel/qeventdispatcher_glib.cpp:160
#18 0xb567e6f8 in g_main_context_dispatch () from /usr/lib/libglib-2.0.so.0
#19 0xb5681da3 in ?? () from /usr/lib/libglib-2.0.so.0
#20 0xb5681f61 in g_main_context_iteration () from /usr/lib/libglib-2.0.so.0
#21 0xb673d478 in QEventDispatcherGlib::processEvents (this=0x8656740, flags={i = -1077912024}) at kernel/qeventdispatcher_glib.cpp:319
#22 0xb6a81ea5 in QGuiEventDispatcherGlib::processEvents (this=0x8656740, flags={i = -1077911976}) at kernel/qguieventdispatcher_glib.cpp:198
#23 0xb671152a in QEventLoop::processEvents (this=0xbfc05ed0, flags={i = -1077911912}) at kernel/qeventloop.cpp:143
#24 0xb67116ea in QEventLoop::exec (this=0xbfc05ed0, flags={i = -1077911848}) at kernel/qeventloop.cpp:194
#25 0xb6713da5 in QCoreApplication::exec () at kernel/qcoreapplication.cpp:845
#26 0xb69e7767 in QApplication::exec () at kernel/qapplication.cpp:3331
#27 0xb7f87ce1 in kdemain (argc=1, argv=0xbfc060a4) at /build/buildd/kdebase-workspace-4.1.85/plasma/shells/desktop/main.cpp:58
#28 0x08048712 in main (argc=) at /build/buildd/kdebase-workspace-4.1.85/obj-i486-linux-gnu/plasma/shells/desktop/plasma_qgv_dummy.cpp:3