Quote Originally Posted by unix111 View Post
OpenGL 3 never worked for my KDE setups […] Remembering a few years ago with OpenGL 3.1, I got weird hang-ups, some pixel noise and garbled-up desktop icons …
After posting this last week, I thought I should give the OpenGL-3.1 option in the Plasma Compositing settings another chance.

I am glad to report that the problems I previously experienced seem to have vanished. At least one of the updates during recent months seem to have improved things on my main rig. I'll keep using KDE with OpenGL 3.1 and keep you informed. Thank you, morera, for giving us status updates and thus bringing back into focus my own postponed kwin/Plasma/kdm-related experiments for me — postponed until now, that is. Cheers!