[UnrealEd]

I just tested your code on my pc, and it worked just fine, the only thing i changed was adding single quotes around the url:

mybtn.onRelease = function (){
    var url:String = "http://www.google.com";
    getURL ("javascript:NewWindow=window.open('"+url+"','newWin','width=400,height=300,left=0,top=0,toolbar=No,location=No,scrollbars=No,status=No,resizable=No,fullscreen=No'); NewWindow.focus(); void(0);");
}; 

I tested this in Mozilla Firefox, and mozilla gave me the "the website tries to open a popup" notification

Cheers

PS: are you dutch speaking? cause i found the same code on a Dutch forum, named Flashfocus. This is the url of the thread: http://www.flashfocus.nl/forum/showt...+nieuwe+window