Thanks for all the work on dojo 1.2 by the way - fixed ALOT of issues I was having :-)
I notice there are a few enhancement requests for the Tree widget - I'm specifically interested in trac 1313.
I have extended the current Tree widget to include checkboxes, selection cascades and 'checked' data bindings from the Tree's store. I would rather not have to re-code all this again for the Tree in 1.2 and I notice in the trac comments that the tree may be enhanced with extra functionality by using mixins. Can I get an idea from the dojo committers on how they see enhancements being added to the tree in 1.3? Will the Tree stay as is and new functionality be added by mixins? If so, has there been any thought about:

adding multiple mixins to the tree and conflict resolution between mixins?
how to alter the existing tree's templateString if the mixin needs more dom nodes?
whether the mixins override existing methods and then call inherited(arguments) or listen for events raised from the base class's functions?

Personally, I think this could get very messy if you added new dom nodes to the tree / treeNodes as you would have to override everything from keypress handlers to the A11Y code and you would practically be re-writing the existing widget.