Provide an API for filtering the TreeView.

Imagine large list of expanded and collapsed items which completely does not fit on the screen in RadTreeView. User scrolls to the middle of the list. User doesn't select anything from the list, just looks. User closes the application, and the application saves TreeView's current scroll positions in some file. Next user opens the application. After items are loaded I want to scroll RadTreeView in code to the position from the previously saved data in file.

Context menu would be useful to allow users to add / delete items.