I've been dealing with an issue for awhile now where dragging and dropping multiple tree items is kind of difficult. If I select several items and then try to drag them somewhere else, it only works if I start the drag with my mouse over the last item selected. If I try to start the drag with my mouse over any other selected items then the tree selection changed event fires and wipes out all of the selected items except for the one I'm currently over.
Holding the shift key during all of this also makes it work as expected. But both of the ways that work aren't very obvious to users. Is there any other way to keep all of the selected items when dragging regardless of what item the drag starts over?
Do you have a demo that shows tree drag and drop with multi-select? The one I have installed only has single selection, so I can't tell if it's something present outside of my application.
My application doesn't seem to be doing anything strange with selection on right-click, but I can take the sample application and add multi-select support to see if the same issue occurs.
The TreeView Drag and Drop demo has single selection enabled by default, but you can change this by setting the SelectionMode property of the RadTreeView in the example to Multiple (or Extended). I've double checked this and the drag/drop in the demo works properly with the multiple selection enabled.
You can test this also in the following example: https://github.com/telerik/xaml-sdk/tree/master/TreeView/DragDropBetweenTreeViews