title: Not able to handle PreviewMouseDown
body: <p>Hey; I have the following visual hyerarchy in a usercontrol:</p>
  
  <p>Grid -> Canvas -> MyContentControl</p>
  
  <p>MyContentControl is a class derived from ContentControl that has an adorner on top that is a rectangle, this is to make it easier to click on certain objects (increase hit testing area). The adorner is present at all times, but with transparent background.</p>
  
  <p>I would like to see the PreviewMouseDown events raised when I click on a MyContentControl from the usercontrol's codebehind, but the event does not seem to be raised there, only at the adorner level.</p>
  
  <p>The event is handled at the adorner level, but e.IsHandled is not set to true, so it should continue bubbling or tunneling. From what I read, PreviewMouseDown is tunneling, and IIRC, it should have been raised at the usercontrol first.</p>
  
  <p>Am I missing something?</p>
  
  <p>Thank you.</p>