Steps to reproduce the issue:

1. Run the example app.
2. Click undo (the last item is removed).
3. Click redo (the last item should be added to the Treeview, it does not)
If I run the application and click undo twice and then redo twice, the things work. The Treeview is not updated if I add and remove the same element instance to the binding list.

Workaround: rebind the treeview after redo or create a new instance of the Element class with the same name and id.