X11: run a gnome app as another user

Question

I have ubuntu + x11 + gnome.

I want to run a graphical application as another user.

However, when I start it from the command line using sudo -u otheruser app I get the error "No protocol specified".

How can I work arround this?

Answer 1

xhost '+si:localuser:USERNAME'

Answer 2

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 -