I encountered a bug in IE6 where the z-index of <select> elements is always higher than of other elements, regardless of their z-index, i.e. <select> elements always appear on top of everything else. This is a problem for PMA because the tooltip feature becomes blocked and you can't read the text inside:
http://lorilee1.files.wordpress.com/2010/08/ie_edit-e1280869355294.png http://lorilee1.files.wordpress.com/2010/08/ie_export-e1280869331806.png
http://lorilee1.files.wordpress.com/2010/08/ie_export-e1280869331806.pngThe fix for this is to position an iframe directly on top of every single <select> element to just cover it, though it's really just an hack.
I'm wondering if it's even necessary to continue supporting IE6. (Google stopped supporting it for YouTube...)