title: Draw semi transparent overlay image all over the windows form having some controls
body: <p>Draw semi transparent overlay image all over the windows form having some controls such that all its child controls should be visible but you can't click them. It should just like we see some things through some semi transparent black mirror.</p>
  
  <p>I have tried using Transparent control. That is sub-classing Panel control and drawing image over that control, however all the controls are fully visible.</p>