How to run an Xwindow Application as another user?

$ xhost +SI:localuser:<user-to-run-as>

Then you can do:

$ sudo su - <user-to-run-as>

And lastly, run your app:
$ krusader

Or

Execute this command first: $ sudo xhost + Then run the command you want as the other user: $ sudo -i -u username $ command you want to run When you are done: $ sudo xhost -

http://stackoverflow.com/questions/1124171/x11-run-a-gnome-app-as-another-user

http://askubuntu.com/questions/5410/how-to-run-an-application-as-another-user