display identifier

From: John Qyindi (qjohnny2000_at_yahoo.com)
Date: 03/13/04

Date: 13 Mar 2004 05:33:47 -0800

Suppose you have 2 different programs running on different computers -
how do you tell if they are displaying on the same screen ?

You could ask them for the values of their DISPLAY variables but these
are often hard to compare b/c some people set the display to the
hostname:0, some to the IpAddress:0, some just to ":0" etc.

Is there some call to X that gives a unique value for a display ... or
some other way you could tell ???