We don't support dragging of nodes between TreeViews at the moment. Drag&Drop actually works only for the nodes in the same RadTreeView. It would be a nice feature for the next release and we would add it to our ToDo list.
It seems that ShowFeedBackForm
property of RadTreeView doesn't work at the moment and it would be fixed for the Q1 SP1
release of RadControls for WinForms.
Thank you for the valuable feedback.