Hi Norbert, thanks to your repsonse!
> Can you try/check the following: > * In the Plasma Settings app, go to > Display and Monitor > Compositor > and check whether > Enable compositor on startup > is selected (on). Indeed, turning that switch to on and restarting helps. Great!!! I cannot remeber that I ever turned it on or off. However, if I turn it back to off, then the problems come back (immedeiately). So at least the latter seems to be a bug, right? (Personally I would not need any 3d effects). In my similar kvm virtualized installtion the switch also is/was off, but there it seems to make no problems, even after a couple of changes and restartings. > Also the rendering backend etc is an important information. Same on bare metal and in vm: skaling method: exact redering backend: OpenGL 3.1 latency: Balance of latency and smoothness tearing: automatic holding available window preview images: only for visible windows allow applications to block compositing: enabled > If the above (after logout/login, or better reboot) does not help: > * Is the behaviour reproducible with a **clean** **new** user? Yes, as turning on Enable compositor on startup immediately helped, I did not try that. Chris
