This example shows how to make DragDrop only fire the onDragDrop event. It will not fire the other stamdard events.
Basically all we are doing is creating a copy of the YAHOO.util.DragDropMgr.fireEvents (YAHOO.util.DragDropMgr._fireEvents) method and creating a new one.
Now, we put some simple logic in the new fireEvents method to call the copy _fireEvents only if the isDrop parameter is set to true.