Comment # 21 on bug 1013550 from Michael Hirmke

Ok, happened earliery than I thought:

Attaching to process 1865
[New LWP 1882]
[New LWP 1904]
[New LWP 2010]
[New LWP 2064]
[New LWP 2085]
[New LWP 2337]
[New LWP 2552]
[Thread debugging using libthread_db enabled]
Using host libthread_db library "/lib64/libthread_db.so.1".
0x00007f30b0b5a640 in QTextLine::layout_helper(int) () from
/usr/lib64/libQt5Gui.so.5

Thread 8 (Thread 0x7f2ffe181700 (LWP 2552)):
#0  0x00007f30afc7749d in poll () at /lib64/libc.so.6
#1  0x00007f30ac33f314 in  () at /usr/lib64/libglib-2.0.so.0
#2  0x00007f30ac33f42c in g_main_context_iteration () at
/usr/lib64/libglib-2.0.so.0
#3  0x00007f30b057e30c in
QEventDispatcherGlib::processEvents(QFlags<QEventLoop::ProcessEventsFlag>) ()
    at /usr/lib64/libQt5Core.so.5
#4  0x00007f30b052bfdb in
QEventLoop::exec(QFlags<QEventLoop::ProcessEventsFlag>) () at
/usr/lib64/libQt5Core.so.5
#5  0x00007f30b0366f1a in QThread::exec() () at /usr/lib64/libQt5Core.so.5
#6  0x00007f2fff5a98f7 in KCupsConnection::run() () at
/usr/lib64/libkcupslib.so
#7  0x00007f30b036b9e9 in  () at /usr/lib64/libQt5Core.so.5
#8  0x00007f30af981734 in start_thread () at /lib64/libpthread.so.0
#9  0x00007f30afc7fd3d in clone () at /lib64/libc.so.6

Thread 7 (Thread 0x7f300d58f700 (LWP 2337)):
#0  0x00007f30afc7749d in poll () at /lib64/libc.so.6
#1  0x00007f30ac33f314 in  () at /usr/lib64/libglib-2.0.so.0
#2  0x00007f30ac33f42c in g_main_context_iteration () at
/usr/lib64/libglib-2.0.so.0
#3  0x00007f30b057e32b in
QEventDispatcherGlib::processEvents(QFlags<QEventLoop::ProcessEventsFlag>) ()
    at /usr/lib64/libQt5Core.so.5
#4  0x00007f30b052bfdb in
QEventLoop::exec(QFlags<QEventLoop::ProcessEventsFlag>) () at
/usr/lib64/libQt5Core.so.5
#5  0x00007f30b0366f1a in QThread::exec() () at /usr/lib64/libQt5Core.so.5
#6  0x00007f30b41f6632 in  () at /usr/lib64/libQt5Quick.so.5
#7  0x00007f30b036b9e9 in  () at /usr/lib64/libQt5Core.so.5
#8  0x00007f30af981734 in start_thread () at /lib64/libpthread.so.0
#9  0x00007f30afc7fd3d in clone () at /lib64/libc.so.6

Thread 6 (Thread 0x7f3098443700 (LWP 2085)):
#0  0x00007f30af9860af in pthread_cond_wait@@GLIBC_2.3.2 () at
/lib64/libpthread.so.0
#1  0x00007f30b5e4593b in  () at /usr/lib64/libQt5Script.so.5
#2  0x00007f30b5e45969 in  () at /usr/lib64/libQt5Script.so.5
#3  0x00007f30af981734 in start_thread () at /lib64/libpthread.so.0
#4  0x00007f30afc7fd3d in clone () at /lib64/libc.so.6

Missing separate debuginfos, use: zypper install
plasma5-workspace-debuginfo-5.8.6-8.1.x86_64

I guess, you'll need mot infos, though.
Should I install the debuginfo package and try again? Or is the output above
sufficient?
An perhaps another interesting information: With Desktop Theme "Breeze" the
problems seems to occur not as often as with "Air openSUSE".