run program with another user how?

[Arthur Bela]

I want to use an application with wine, but not with the user logged
in -> with another user [it would be a """chroot""" ~like "thing" :D -
because i don't trust the app...]:

i set the permissions:

chmod 705 -R ANOTHERUSER/

gksu -u ANOTHERUSER xcalc

it asks for a password, i type in the correct passwd, but nothing happens.

What am i doing wrong? :(

it doesn't give any error messages, that i can "google".. :\

thank you for any tips