title: Making a transparent hole in an overlay WPF
body: <p>I am trying to replicate the effect below in WPF. I have a Grid control, within it a border background color of #000000, with opacity of 0.7 and a content presenter like so...</p>
  
  <pre><code>&lt;Grid&gt;
      &lt;Border Background="#000000" Opacity="0.7" /&gt;
      &lt;ContentPresenter ... /&gt;
  &lt;/Grid&gt;
  </code></pre>
  
  <p>I put an ellipse for content of my control to try to get the effect but I have reached a road block from there.</p>
  
  <pre><code>&lt;Control:SomeControl&gt;
      &lt;Ellipse Fill="Transparent" /&gt;
  &lt;/Control:SomeControl&gt;
  </code></pre>
  
  <p>Any help is appreciated.</p>
  
  <p><a href="https://i.stack.imgur.com/pWHa4.jpg" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/pWHa4.jpg" alt="enter image description here"></a></p>