Created attachment 96795 [details]
xsession error log

kwin_x11 crashes at every opportunity, even more often than kwin itself does. There are tons of reports for that but I found none for the really annoying part of this:

In contrast to kwin, kwin_x11 doesn't respawn.

## Situation after crash

After a crash, the situation is as follows:
- The content of an opened window is still there to interact with, but its frame and title bar is gone.
-  Most of the time I can't interact with the windows via keyboard, like closing it with [Strg+q]
- The screen state stays the same if I switch Activities or Virtual Desktops.
- Other that a lot of XBM error 3 (BadWindow), which are always there, there is no mention of any problems with kwin or x_11 in journalctl.

## State of process kwin_x11 after crash
In the process tree, kwin_x11, child of ksmserver, is STOPPED. Sending the CONT signal doesn't change anything on the desktop; only effect is that the process now uses ~ 50% of CPU without doing anything.

## .xsession-errors
.xsession-errors is the only source I found, that gives a hint on why kwin_x11 doesn't respawn:

    KCrash: Application 'kwin_x11' crashing...
    KCrash: Attempting to start /usr/lib/drkonqi from kdeinit
    KWin: Manager-Auswahl nicht möglich. Läuft ein anderer Fenstermanager? (Versuchen Sie es mit --replace)

(Last line says: KWin: Manager-selection not possible. Is another windows-manager running? (Try with --replace))
Full log in attachments [lines 244 - 246].

## Workaround
I have to restart kwin_x11 with
    DISPLAY=:0 kwin_x11

--replace is not necessary and makes no visible difference.
Now kwin_x11 runs as child of whatever process I used to respawn it (in my case dolphin).
Remarkably, it runs a lot more stable now, sometimes not crashing for days, in contrast to barely 15 minutes after a system boot.

If I can do anything to help investigate and solve the problem, please let me know.