Tree view for tag sugestions

Hi,

Thanks for this great module!

I would like to suggest some kind of integration with taxonomy super select, so it can be used with non-free tagging vocabularies. When you have a large vocabulary, it helps to browse an hierarchy, yet the ajax search is of real value.

So, an option to show and navigate suggestions over category tree (like super select module) would be a great addition.
This would be usable with non-free tagging vocabularies, so an option not to add new tags should also be there.

Thanks