Comment # 10 on bug 1205742 from Robin Klitscher

(In reply to Fabian Vogt from comment #9)
> (In reply to Robin Klitscher from comment #8)
> > (In reply to Fabian Vogt from comment #5)
> > > You can try to run "kwin_x11" manually and/or look at "systemctl --user
> > > status plasma-kwin_x11.service".
> > 
> > kwin_x11 returns:
> > 
> > ���������kwin_x11: symbol lookup error: /usr/lib64/libkwin.so.5: undefined symbol:
> > drmModeFormatModifierBlobIterNext���������
> 
> That means you did not switch over all packages to the KDE repos. You *must*
> set them as higher priority (lower value) than other repos and run "zypper
> -v dup --from <KDE:Frameworks repo name>".

Thank you.  All good now.    

I did it using the Yast2 GUI by reselecting the "Switch systems packages to the
versions in this repository" for the relevant repositor(ies).  This which
marked a small number of additional packages for update, and it worked.  So it
seems that somewhere along the line the switch to those repositories that I'd
previously selected had stopped working properly.

We live and learn.  I'm now a happy camper and I do appreciate your expert
help.