title: Placed over special UI, but special UI appears through (unclickable)
body: <p>I opened a new window, I made it fullscreen and then set it to always on top with <code>XSendEvent</code> on <code>_NET_WM_STATE</code> to set <code>_NET_WM_STATE_ABOVE</code> and then I <code>XFlush</code>'ed. This makes the window appear on top of everything this is great.</p>
  
  <p>Aside: I then draw the screenshot of the desktop to that window and overlay it with a 50% opacity black transparent layer.</p>
  
  <p>So now the issue I am having is that placement is right and it is correct in that it is over the special UI (dock and menu bar) in that you cannot click it. But when I click in the window, the special UI just <em>appears</em> through. You cannot click on it, it is just appearing above my window.</p>
  
  <p>Is there any window properties I can set to fix this issue?</p>
  
  <h1>Here is a screenshot showing before I click in the window:</h1>
  
  <p><img src="https://i.imgur.com/SIW8XLe.png" alt=""></p>
  
  <h1>Here is screenshot showing after i click in the window, the special ui appears through (while not clickable - which is good)</h1>
  
  <p><img src="https://i.imgur.com/JDrHTzR.png" alt=""></p>
  
  <h1>Replication</h1>
  
  <p>I can replicate this situation exactly on your system. Its a released firefox addon. Let me know please and we can chat using stackoverflow and i can walk you through to replicate.</p>