title: TreeView notification error when the TVN_ENDLABELEDIT notification handler is being debugged
body: <p>I have a TreeView that allows users to change the labels. To do this I have a handler for the  TVN_ENDLABELEDIT notification that reads the TVITEM from the NMTVDISPINFO structure and sends the TVM_SETITEM message.</p>
  
  <p>All of this works fine EXCEPT in one particular case: when for the sake of debbuging I interrupt the execution of the handler BEFORE returning with 0 from the notification.</p>
  
  <p>What happens in this case is that if another notification arrives before the handler returns with 0, i.e., before I'm done debbuging it, the TreeView will crash the application because it will call a rutine at a null pointer.</p>
  
  <p>This means that the TreeView somehow trusts the handler from finishing before other event gets processed.</p>
  
  <p>Has anyone experienced this kind of behavior? I think the OS should be a little bit more robust; shouldn't it?</p>