title: WPF Clear Region on a Drawing Context?
body: <p>So I am producing a transparent PNG using a DrawingContext and DrawingVisual.</p>
  
  <p>Inside the DrawingContext, I drew a rectange.</p>
  
  <p>I would now like to "cut out" a circle inside of the rectangle. How do I do this? I did not find any functions in drawing context to clear a region.</p>