ghostbunny 
Let’s take it by points too:
at first: you are right. Sorry...
second: libxfce4utils wasn’t marked as having a update, so, what I did was reinstall it
third: task-xfce and task-xfce-plugins were installed; I reinstalled them too
fourth: garcon/libgarcon were also installed
fifth:
”PS:
I'm German. Sorry because of possible mistakes in my written messages xD”Ich bin auch ein Deutscher (66,6%

, doch nicht geboren in Deutschland) aber, schade, Ich spreche es nicht...

Vielen Dank für deine Hilfe.
agmgAlso, I reinstalled KDM. Thanks for your help, too.
Now it works, though not very well.... Is it a new version? It looks a little bit different.
Again, thanks for your help, ghostbunny and agmg.
