Just updated to 4.11 and wondering if this is a know bug?
On Mint 14 KDE backports to 4.10.5 was working bug free.
Receive this error when I try to Add New Widget>Get New Widget>Download New Widgets.
Dialog opens then screen goes black and resets and the dialog is gone and panel widgets are locked again.



Any insights or help is appreciated.
Thanks.
.

What information is shown under "Developer Information"? This sounds like a regression of some description.
Also, is anything of relevance printed into ~/.xsession-errors when Plasma Desktop crashes?

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 0x7f5afea92780 (LWP 1923))]

Thread 3 (Thread 0x7f5ae085f700 (LWP 1926)):
#0 0x00007f5af26a0d84 in pthread_cond_wait@@GLIBC_2.3.2 () from /lib/x86_64-linux-gnu/libpthread.so.0
#1 0x00007f5af7fb0987 in ?? () from /usr/lib/x86_64-linux-gnu/libQtScript.so.4
#2 0x00007f5af7fb09b9 in ?? () from /usr/lib/x86_64-linux-gnu/libQtScript.so.4
#3 0x00007f5af269ce9a in start_thread () from /lib/x86_64-linux-gnu/libpthread.so.0
#4 0x00007f5afe371ccd in clone () from /lib/x86_64-linux-gnu/libc.so.6
#5 0x0000000000000000 in ?? ()

Thread 2 (Thread 0x7f5a5a1c7700 (LWP 1927)):
#0 0x00007f5afe366313 in poll () from /lib/x86_64-linux-gnu/libc.so.6
#1 0x00007f5af1f9dd84 in ?? () from /lib/x86_64-linux-gnu/libglib-2.0.so.0
#2 0x00007f5af1f9dea4 in g_main_context_iteration () from /lib/x86_64-linux-gnu/libglib-2.0.so.0
#3 0x00007f5afaf59c46 in QEventDispatcherGlib::processEvents(QFlags<QEventLoop::ProcessEventsFlag>) () from /usr/lib/x86_64-linux-gnu/libQtCore.so.4
#4 0x00007f5afaf2a2ef in QEventLoop::processEvents(QFlags<QEventLoop::ProcessEventsFlag>) () from /usr/lib/x86_64-linux-gnu/libQtCore.so.4
#5 0x00007f5afaf2a578 in QEventLoop::exec(QFlags<QEventLoop::ProcessEventsFlag>) () from /usr/lib/x86_64-linux-gnu/libQtCore.so.4
#6 0x00007f5afae2bb40 in QThread::exec() () from /usr/lib/x86_64-linux-gnu/libQtCore.so.4
#7 0x00007f5afaf0a9df in ?? () from /usr/lib/x86_64-linux-gnu/libQtCore.so.4
#8 0x00007f5afae2eb1c in ?? () from /usr/lib/x86_64-linux-gnu/libQtCore.so.4
#9 0x00007f5af269ce9a in start_thread () from /lib/x86_64-linux-gnu/libpthread.so.0
#10 0x00007f5afe371ccd in clone () from /lib/x86_64-linux-gnu/libc.so.6
#11 0x0000000000000000 in ?? ()

Thread 1 (Thread 0x7f5afea92780 (LWP 1923)):
[KCrash Handler]
#5 0x00007f5afcb1ddd4 in QDeclarativeItem::~QDeclarativeItem() () from /usr/lib/x86_64-linux-gnu/libQtDeclarative.so.4
#6 0x00007f5a5f9dac01 in ?? () from /usr/lib/kde4/imports/org/kde/plasma/core/libcorebindingsplugin.so
#7 0x00007f5afaf40498 in QObject::event(QEvent*) () from /usr/lib/x86_64-linux-gnu/libQtCore.so.4
#8 0x00007f5afa2d2e9c in QApplicationPrivate::notify_helper(QObject*, QEvent*) () from /usr/lib/x86_64-linux-gnu/libQtGui.so.4
#9 0x00007f5afa2d730a in QApplication::notify(QObject*, QEvent*) () from /usr/lib/x86_64-linux-gnu/libQtGui.so.4
#10 0x00007f5afbbe4906 in KApplication::notify(QObject*, QEvent*) () from /usr/lib/libkdeui.so.5
#11 0x00007f5afaf2b59e in QCoreApplication::notifyInternal(QObject*, QEvent*) () from /usr/lib/x86_64-linux-gnu/libQtCore.so.4
#12 0x00007f5afaf2f421 in QCoreApplicationPrivate::sendPostedEvents(QObject*, int, QThreadData*) () from /usr/lib/x86_64-linux-gnu/libQtCore.so.4
#13 0x00007f5afaf59a93 in ?? () from /usr/lib/x86_64-linux-gnu/libQtCore.so.4
#14 0x00007f5af1f9dab5 in g_main_context_dispatch () from /lib/x86_64-linux-gnu/libglib-2.0.so.0
#15 0x00007f5af1f9dde8 in ?? () from /lib/x86_64-linux-gnu/libglib-2.0.so.0
#16 0x00007f5af1f9dea4 in g_main_context_iteration () from /lib/x86_64-linux-gnu/libglib-2.0.so.0
#17 0x00007f5afaf59c26 in QEventDispatcherGlib::processEvents(QFlags<QEventLoop::ProcessEventsFlag>) () from /usr/lib/x86_64-linux-gnu/libQtCore.so.4
#18 0x00007f5afa377c1e in ?? () from /usr/lib/x86_64-linux-gnu/libQtGui.so.4
#19 0x00007f5afaf2a2ef in QEventLoop::processEvents(QFlags<QEventLoop::ProcessEventsFlag>) () from /usr/lib/x86_64-linux-gnu/libQtCore.so.4
#20 0x00007f5afaf2a578 in QEventLoop::exec(QFlags<QEventLoop::ProcessEventsFlag>) () from /usr/lib/x86_64-linux-gnu/libQtCore.so.4
#21 0x00007f5afaf2f738 in QCoreApplication::exec() () from /usr/lib/x86_64-linux-gnu/libQtCore.so.4
#22 0x00007f5afe67a3f1 in kdemain () from /usr/lib/kde4/libkdeinit/libkdeinit4_plasma-desktop.so
#23 0x00007f5afe29f76d in __libc_start_main () from /lib/x86_64-linux-gnu/libc.so.6
#24 0x00000000004006d1 in _start ()

Also finding Clementine going bonkers and deleting items in current playlist and flickering and doing nothing but weirdness.
Installed Amarok and is plain crashing also.

This is quite unusual behaviour - a crash such as the one you posted above shouldn't happen.

Given the problems faced by Clementine and Amarok, can you verify all Qt packages are of a consistent version, and that all KDE packages are up to date and come from a single source (same repository). Qt should ideally come from the same source as KDE.

try install update all KDE packages, it can recover your system.

i think that is a bug guys