Thanks for the quick reply.
1. You are correct. http://demos.telerik.com/silverlight/#DragAndDrop/TreeToGrid
is working fine now. That is really weird, but I'll take it! (Still have a problem with childwindows, though).
2. We are using RadDragAndDropManager (not DradDropManager) because we want auto-scrolling.
3. Your advice on ExcutionMode = Legacy made our MainWindow auto-scroll consistently, but not the ChildWindow.
4. With the exact same code (simply swapping out the dlls) we see this behavior, using RadDragAndDropManager. MainWindow and ChildWindow share the same code, but ChildWindow does not seem to work.
Version ExecutionMode MainWindow Scrolling ChildWindow Scrolling
2010.1.515.1040 n/a YES no
2011.2.0712.1040 Legacy YES no
2011.2.0712.1040 Default no no
5. I uploaded a solution via a support ticket (458309) using a ListBox to demonstrate that the ChildWindow does not do auto-scrolling. Can you show me how to enable auto-scrolling on the ChildWindow, too?