[Javascript] How can I test to seee if a popup window has already been opened?

[.ben]

Hi.  I need to check to see if a popup window has been opened.  If I was
using a frameset this would be pretty straightforward as I could use a flag
to check if is opened/closed.  Problem is that i'm not using frames and the
page that loads this popup may not be the same page that references it later
on.

How can I check to see if it is already open?  If it is I need to rezise
it... if it's not I need to open it with specific dimentions (which I am ok
with).

Any ideas?

Cheers,

 .ben