Solution:
- Create a new Application Button with Mouse-right-klick Menu
- add at command line
gnome-session-save --kill
- and now take you loved icon at /usr/share/icons/
- it is very good for Kids PCs or public Internetstations cause you can remove the Systemmenubars
Loesung:
- Mit dem Kontextmenue der Maus einen neuen Starter Knopf am Desktop erstellen
- aus /usr/share/icons das Logoff Icon aussuchen
- in die Komandozeile
gnome-session-save --kill setzen