title: C# graphics draw transparent rectangle over area
body: <p>I have two images layered ontop of each other and want to be able to clear a section of the top image. Normally if I wanted to clear a section of an image I would just paint it the background color by doing</p>
  
  <pre><code>g.FillRectangle(Brushes.White,x,y,width,height);
  </code></pre>
  
  <p>but if I do that on the top image that area of the bottom image gets covered by the white rectangle. I tried doing </p>
  
  <pre><code>g.FillRectangle(Brushes.Transparent,x,y,width,height);
  </code></pre>
  
  <p>but that does not seem to clear the region of all of it's previous contents. Is there any way I can make the pixels in that region transparent?</p>