RadTreeView supports drag-and-drop functionality for tree-nodes. To enable this mode you need to mark the instance of RadTreeView with the AllowDragDrop="True" attribute and you'll be able to drag and drop tree-nodes. A visual indication shows the position of a node if dropped (above, below, within).

When RadTreeView detects a valid drag-and-drop operation (the selected node is dropped onto another node) it generates an event which you can use to perform specific action, by fetching both the source and destination drag/drop nodes.