title: How can I tell if a drag and drop operation failed?
body: <p>It seems to me there is no way to detect whether a drag operation was successful or not, but there must be some way. Suppose that I want to perform a "move" from the source to the destination. If the user releases the mouse over some app or control that cannot accept the drop, how can I tell?</p>
  
  <p>For that matter, how can I tell when the drag is completed at all?</p>
  
  <p>I saw <a href="https://stackoverflow.com/questions/480156/how-do-i-tell-if-a-drag-drop-has-ended-in-winforms">this question</a>, but his solution does not work for me, and <code>e.Action</code> is <em>always</em> <code>Continue</code>.</p>