[jQuery] Check if window exists before opening

[Bruce MacKay]

Hello folks,

I can't find the answer I need in the archives (Nabble), so my 
question is how do I check to see if a window exists before I open it?

When a user of my application clicks on a help link, I want the help 
file to load into a new window.  I'm doing that via...

        $("a.openW").click(
         function() {
             window.open(this.href); return false;
         });

But I want to first make sure that a window containing the help file 
isn't already open before a new one (another one) is opened.

Help/direction appreciated.

Thanks,

Bruce