Running kcmshell5 kwineffects and clicking on one of the movie icons leads to a segfault. Unfortunately, I don't even know what that icon should do, supposedly a preview? Reproducible: Always
Can you provide a backtrace ("developer information" from the crash dialog)?
That's the strange thing: I don't get this dialog offering me to make a backtrace. I have the debuginfo/symbols of kwin installed and I tried to run it from gdb, but the traceback I got (~50 levels; the longest traceback I had seen so far) does not look very useful to me. Could you give me instructions on how to get a useful backtrace (or was the gdb method OK?)?
gdb should be fine, maybe it's required to have it for all threads ("thread apply all bt") - just attach it: we'll then figure whether we require more info.
Created attachment 97332 [details] Backtrace
gstreamer -> libsoup -> libproxy, dlopens kdelibs (KDE4) => Qt4/Qt5 symbols in one process: boom. See bug #346209 on more details - no idea where "modules/config_kde4.so" comes from (isn't installed here, maybe downstream thing of parallel KDE4/KDE5 installation) *** This bug has been marked as a duplicate of bug 323407 ***
@Thomas Mitterfellner: which distribution are you using?
I'm using openSUSE Leap 42.1 but I did a distribution upgrade from 13.2, so maybe that's the reason for the mixed symbols. Unfortunately, I don't know what I have to uninstall and whether it would actually be possible because of some applications depending on kde4 libs still.
rpm -qf /usr/lib/libproxy/0.4.11/modules/config_kde4.so should be "libproxy1-config-kde4" Upstream bug report is https://code.google.com/archive/p/libproxy/issues/197 and they're wrong about KDE symbol versioning - the problem is in the Qt libs.