In the current developer preview 1 the treestore has a private inner class TreeModel.
When trying to extend things you run into the problem that a) TreeModel is not visible to outer classes and b) is not a ModelData (or Map-style) class any more.

Maintaining additional information in other way then applying it to the wrapper directly is possible, but also more complex.

It would be of great use if one could overwrite a delegate creating the TreeModel to be able to create additional data/behavior by subclassing the TreeModel class.

Do you think this makes sense?