Acorn suggests this approach:

Instead of pop-ups, I recommend:

You need a landing page with an IFRAME. Its width will be that of the Insert pages.
Placeholder Body is:
<iframe src="sub1.htm" width="100%" height="100%" frameborder="0" scrolling="no" id="panel" name="iframe_panel" ><p>Your browser does not support iframes.</p></iframe>

where sub1.htm is the filename of the first insert and where panel is the important Name to allow linking from the landing page into the IFRAME.

You need some Page Head code:
<script>function loadintoIframe(iframeid, url){
if (document.getElementById)

Finally, to link from each button, you need: javascript:loadintoIframe("panel", "sub1.htm"); - changing sub1.htm to the filename of each Insert.

The clicking of any button will open the connected Insert within the IFRAME and it always opens at the top of its sub-page.