CSS Properties
Internet Explorer 5.0+
SELECT lists do not obey the normal z-index stacking order. Nothing can be placed "on top of" a SELECT list unless it is another SELECT list with a higher z-index. Other elements are always rendered below SELECT lists, even if they are given a higher z-index value than the SELECT. (IE4 has this behavior too, but it cant even render other SELECT lists properly with z-indexes assigned.)