A listener interface for receiving mouse motion events during a drag operation.
The class that is interested in processing mouse motion events during a drag operation either implements this interface or extends the abstract DragSourceAdapter class (overriding only the methods of interest).
Create a listener object using that class and then register it with a DragSource. Whenever the mouse moves during a drag operation initiated with this DragSource, that object's dragMouseMoved method is invoked, and the DragSourceDragEvent is passed to it.