I made some progress with popups under IE.

1- The content of the inner document still shows about halfway across the iframe under IE6 through IE8.

I found that if I set 'position: 0px' instead of 'relative' for 'content.css'  in SF_popupform.js (line 233) - the content is displayed correctly both in IE and Firefox (I haven't looked at Chrome yet).

2- Something is terribly slow in SF_popupform.js under IE.

Displaying the content inside of the iframe takes 3 to 4 times longer in IE than in Firefox. I suspect it has to do with the way the 'clean up' of the page is happening. Maybe there is a more efficient way to extract the content area. I have read articles about how javascript can be very inefficient in IE but I haven't identified the bottleneck yet.

- Laurent Alquier