finding process id of a window

[Joel Dice]

On Mon, 28 Mar 2005 Yossi.Itzkovich at ecitele.com wrote:

> I have few  X applications, started from the command line with identical
> command line, but each has a different DISPLAY environment variable.
> Is there a way to get the process id of a process from its window ?

I asked about this a few months ago, and apparently it's not possible. 
What do you need the process id for?  Perhaps what you're trying to do can 
be accomplished some other way.

  - Joel