For various reasons, it is hard to access a (frameset) frame in a popup window that you just opened. So what you want to do is store information in the popup window and let it perform whatever action needed itself:
Parent window:
popup = window.open(url,name,options); popup.parameters = ...
Popup window:
<frameset onload="performAction(top.parameters)"> <frame ...> </frameset>
If you actually need to access a frame, you should do it the same way. I.e. put the actual functionality in the frame window:
<body onload="performFrameAction(window.frameParameters)"> ... </body>