When older IEs throw an error at setting the background-color using RGBA, use something they understand.
Set zoom=1 on the dialog element, in order to trigger hasLayout for older IEs and show the element.
Do not try to dispatch a custom "close" event in older browsers (such as IE) that do not support doing so.
Find the index of the dialog in the stack, for those browsers that do not support "indexOf"
Catch exceptions thrown by IE when attempting to focus on elements.