Display an X program running on another computer

1. Authorize the remote host to display the output to your current X server with:
   xhost +ip-address-of-remote-computer
2. SSH into to the remote computer.
3. Set the DISPLAY environment variable on the remote computer to point to the root window of the local X server:
   DISPLAY=ip-address-of-local-computer:0.0
   This represents hostname:displaynumber.screennumber.
4. Start the X client program on the remote computer in the background and the output will be displayed on the local computer.
   xcalc &
   X does not have to be running on the remote computer for the display output to be sent across the network.

Run an X program as root while using X as a user

From the console, disable X security allowing any user to connect to the X Window System root window (the root window is not related to the root user):
xhost +
Then, su to root and start the program:
xterm &

List all installed fonts:

xlsfonts