Comment # 4 on bug 915661 from Freek de Kruijf

(In reply to Hrvoje Senjan from comment #3)
> WM = window manager. so either try e.g. openbox --replace & from within
> plasma session, or change default WM in systemsettings5 -> Applications

Today I performed another zypper up and got ... openSUSE 20150129!! with 149
updated packages, some NOT from main repository.
Most likely the update yesterday was only partial. Now everything seems to be
back to normal. Hence solved!