Parameters
- pt
- normally the current mouse point, in model coordinates
- moving
- copying
If DropOntoEnabled is true, this looks for a Northwoods.GoXam.Part at the mouse point for which ConsiderDragOver is true; if successful it sets DragOverPart to that part.
This method also performs auto-scrolling, if Northwoods.GoXam.Diagram.AllowScroll is true.