hm, I did install now LXQt, it was probably a great error?
After restart, slim is not operable any more. it requires a window manager not beeing in the system (in Debian, I use JWM, because of old SliTaz! I did never understand why people prefer, OVER LXQt etc., somewhat being really a lot greater than JWM and does, at least, enormous less... JWM was our system, is installable, but the adequate menu management, it was present!!!, not any more).
So...
LXQt is installed.
After trying to start, after login, a little windows open an requise those ominous first window manager.
I did install JWM under 'root'
Under root, I can start with LXQt and JWM in the background.
Under "tux", nothing more...
Was is to do correctly to start LXQt after installation?