Hi,

We have added a CancelDrag() method to the 4.2.3 version we are currently preparing for release. You can call this from the BoxModifying event, when the box is outside the currently visible area, to cancel the users action, and than call DoDragDrop to start the drag-and-drop operation. I can send you a prerelease 4.2.3 build if you are interested in trying this out.

Otherwise, you can handle the MouseDown event, and there check if any box is under the mouse cursor. If so, set Behavior = DoNothing so that the control does not start modifying the box, and call DoDragDrop. That will prevent users from selecting and moving boxes, so you might have to implement two modes in your application - one that let users modify the diagram, and one that lets them do drag-and-drop between two diagram.

Stoyan