When using IE, you cannot put an absolutely positioned div over a select input element. That\'s because the select element is considered an ActiveX object and is on top of every
I do the same thing with select boxes and Flash.
When using an overlay, hide the underlying objects that would push through. It's not great, but it works. You can use JavaScript to hide the elements just before displaying an overlay, then show them again once you're done.
I try not to mess with iframes unless it's absolutely necessary.
The trick of using labels or textboxes instead of select boxes during overlays is neat. I may use that in the future.