Starting graphical applications by different users

Launch applications from a graphics X server to which the current user is not the owner.

Normally if a user tries to run a graphics X server from another user gets the following error:

Xlib: connection to ":1.0" refused by server
Xlib: No protocol specified

Error: Can't open display: :1.0

This happens until the owner of the running X server does not grant permission to use his server to other users of the computer with the command "xhost".
For example, if the user owns the running X server wants to give permission to a particular user, he must be running:

xhost +nomeutente

if he wants to authorize all users of the workstation:

xhost +