Most of the admin interface pages and dialogs doesn't validates due to errors in the html such as:

• missing doctypes
• bad nesting of tags (invalid tags in forms, tables missing tr's)
• css/javascript working only in legacy mode due to missing units (px) on css attributes for sizing/positioning

in order to improve compatibility with recent browser we should fix those errors and validate all the code. Working in non-standard mode (no doctype) is really bad for compatibility.

I already started to fix some of the errors for 3.6, and I'll try to fix some more of them. Installing the html validator extension for firefox ( http://users.skynet.be/mgueury/mozilla/ ) is recommended for any developer