Perhaps it is a general linux problem. But how it is possible - like in windows - to change the user in the gui. Perhaps if my son came and want to use the pc for a short time to check his email,.... In windows I can go to change user and than an other desktop will open with for the new user. How can I do this in siltaz. I cannot find anything similar?? I only find this on a console window. But this is no help - not practicable.
I can tell you it's not a general Linux thing. The programme you want to get to, I think, is called a "display manager." It's a graphical front end that looks prettier than a text login: prompt and starts up X Windows for you. The one SliTaz uses is called SLiM. It's pretty bare bones - all that's there is a single field to type in login and password. Perhaps what you need to do is get there again without logging out of the current X session, and I'm not sure how to do that. It won't let me launch it again while X is open, but maybe there's some workaround somebody else can help you with. I hope this response has given you some leads.
lenios from #slitaz has pointed out that you can get another session by pressing Ctrl-Alt-F7, Ctrl-Alt-F8, etc. and login from there, then startx. (Default session seems to be F7.) Thanks, lenios!