I assume you are referring to the approach shown in 'DragDrop' example. Problem is browsers do not raise the dragStart event at all when the diagram captures the mouse from its mouseDown handler. So the example calls setEnabled to  prevent mouseDown handling, but that also stops move and up events which would otherwise show tooltips and detect clicks. Maybe you could let users drag only when some key is held down (e.g. shift) and toggle enabled from the respective keyboard event handlers. Otherwise we could add some property to prevent mouse capture which should then allow for better integration of drag events.

Regards,
Slavcho
Mindfusion