I have the same problem, and I can't achieve to serialize my popup reference.

I tried with JSON and a lot of different libraries :

var popupVar = window.open('url', 'name');
var serializedString = JSON.encode(popupVar);
var serializedString = popupVar.toJSONString();

Every time I have errors. I could catch it with IE, and it says : [Object error]. Great :p
In Firefox it just crashs it...

I did'nt find any real example on serializing JS "native" objects, only JS "created" objects (like var Person = { this.id; this.name; })

Does someone achieve it ? Know how to serialize this popupVar ?

Thanks a lot[/QUOTE]

I have the exact same java script issue where even if my parent window reloads, it should still be able to hold the child window references. Did you manage to get a solution for that. Any help would be appreciated.
Thanks in Advance.