Telling which stack is active?

[Paul Gabel]

Hi everybody:

I have 6 stacks with their windows open at the same time. Some are  
hidden behind other stacks and then slide out from underneath (like a  
drawer). But I can't figure out a way within scripts to tell which  
stack is the "active" one, the one the cursor has last clicked on,  
the one that is checked in the Windows menu. How can I do something  
like: <if stack "ABC" is theActiveStack then ... > ?

This problem is frustrating me, and I sure would appreciate a little  
help.

Paul Gabel