title: Use another control as an opacity mask in WPF?
body: <p>I'm trying to use the OpacityMask property combined with a VisualBrush so that when you drag an image over another control (such as another image, rectangle, or any other control), the part of the image that is over the second control has a different opacity.  That is, the image has some non-zero base opacity, and any part of the image that is over another control has a different (again, non-zero) opacity.  </p>
  
  <p>Is this possible simply using VisualBrush and OpacityMask?  Or is a more complex approach required?  </p>
  
  <p>Thanks!</p>
  
  <p>Edit: I'm trying to make the image have some lower opacity (such as 0.5), and the part being dragged over the control have a higher opacity (such as 1.0).  I originally left out this detail, which is important to the approach taken.</p>