/// <summary>
 /// Handles the <code>DragSourceEvent</code> by invoking
 /// <code>dragExit</code> on listener-a and listener-b.
 /// </summary>
 /// <param name="dse"> the <code>DragSourceEvent</code> </param>
 public virtual void DragExit(DragSourceEvent dse)
 {
     ((DragSourceListener)a).DragExit(dse);
     ((DragSourceListener)b).DragExit(dse);
 }
 /// <summary>
 /// Called as the cursor's hotspot exits a platform-dependent drop site.
 /// This method is invoked when any of the following conditions are true:
 /// <UL>
 /// <LI>The cursor's hotspot no longer intersects the operable part
 /// of the drop site associated with the previous dragEnter() invocation.
 /// </UL>
 /// OR
 /// <UL>
 /// <LI>The drop site associated with the previous dragEnter() invocation
 /// is no longer active.
 /// </UL>
 /// OR
 /// <UL>
 /// <LI> The drop site associated with the previous dragEnter() invocation
 /// has rejected the drag.
 /// </UL>
 /// </summary>
 /// <param name="dse"> the <code>DragSourceEvent</code> </param>
 public virtual void DragExit(DragSourceEvent dse)
 {
 }