I Think I Found a Bug / Multiple Desktops - Window Controls Blank Out /

[mhumm2]

I configured my system to have 4 desktops that I select by putting the cursor on an empty area of a desktop and rolling the scroll wheel. I discovered that when I have multiple desktops populated and I scroll wheel among them, at some point -- anywhere from 2 minutes to 2 hours of use -- all the windows in all the desktops have their window controls --max, min, close-- blanked out. The are not disabled but still visible - just gone. A reboot brings everything back, but it's very inconvenient.

Has anyone else experienced this behavior? I'm using 18.04.3 LTS.

[jlittle]

That's a kwin crash, I think. (Back in the dark days of 15.04 it used to happen to me often; there was a bug somewhere between kwin and the nvidia driver flushed out by the particular nvidia chip I had.) I can provoke that condition using killall -r kwin.

Like plasmashell, you can restart kwin. Unless you are using Wayland it's now called kwin_x11. In a konsole run nohup kwin_x11 &. If you can't get a konsole, press ctrl-alt-f2 to get a linux console, log in, and

$ export DISPLAY=:0
$ nohup kwin_x11 &

and press ctrl-alt-f1 (or f6 or f7, it changed sometime) to get back to KDE.

If it crashes again, there may be something in your set up causing trouble. You could try moving aside the kwin files and directories in .config, or deleting .cache/kwin.

[mhumm2]

Thank you jlittle. And I apologize for the delay in responding. I have that written down and will use it if it happens again. In the meantime I will clear the cache.