xhost + works like a charm. The only thing is that you have to type it every time you login into your system. To make this permanent, just add the following line to ~/.profile:

xhost +

then type in the terminal

$ . ~/.profile

This will make sure you don't have to type the command every time you login. The catch - this work only for you, not for other users.

If you want this to be enabled syste-wide, then add the above line to /etc/profile and type # . /etc/profile. You are up and running. Happily work with any GUI app run as root.