What is the equivalent of window.createPopup() in Firefox Safari chrome etc

Question

It seems that I can't use window.createpopup on other browsers because its not supported. the reason why i was using window.createpopup is because it can popup from one frame and show on top of another frame on the same page. I am using frameset, so this wasnt possible with other types of dropdown menues. is there anything else i can use which could achieve the same objective (ppup or dropdown from one frame and on top of another)?

edit:

I am not using iframes for frameset

here is how my frameset looks like

</head>
    <frameset id="frameMain" rows="84,*" framespacing="0">
       <frame src="pageHeader.html" id="mail" name="mail" frameborder="0" border="0" marginwidth="0" marginheight="0" noresize="noresize" scrolling="no"/>
       <frameset id="frameSet" cols="126,*" framespacing="0">
           <frame src="page2.html" id="leftnav" name="leftnav" frameborder="0" border="0" marginwidth="0" marginheight="0" noresize="noresize" scrolling="no"/>
           <frame src="empty.htm" id="main" name="main" frameborder="0" border="0" noresize="noresize" scrolling="yes"/>
       </frameset>
    </frameset>
</html>

I want my dropdown menuto be in 'frameMain' and show over the other frames, and not behind them

Solution

I am not sure if this will help in your case - I didn't try it like that, but I have implemented a cross browser window.createPopup(), that will work on all major browsers: Firefox, IE, Chrome, Safari.

Here is my article with all the details and the code needed: http://extremedev.blogspot.com/2011/01/ie-windowcreatepopup-cross-browser.html

Leave a comment there so that I know if it helped, otherwise, tell me what is the problem and we will try to find a solution.