If there is user demand for it, we can certainly add it to our todo list!
Can you describe in more detail what you mean by “XHTML Support”? We’ve found in the past that when someone requests a new feature, his/her view of what ‘support’ for it could mean something completely different that another user’s view of what ‘support’ meant for it.
The more information you provide us with, the more likely it is that we’ll be able to address your needs.