title: WPF Popup UI showing black
body: <p>I am using a WPF Popup control, and it is showing the background as black. I put a StackPanel inside it with Background=&quot;Transparent&quot;, but that does not help.</p>
  <pre><code>&lt;Popup PlacementTarget=&quot;{Binding ElementName=parentStackPanel}&quot; Placement=&quot;Center&quot;
          IsOpen=&quot;False&quot; Name=&quot;m_popWaitNotifier&quot; PopupAnimation=&quot;None&quot; 
          AllowsTransparency=&quot;False&quot;&gt;
      &lt;StackPanel Orientation=&quot;Vertical&quot; Background=&quot;Transparent&quot;&gt;
          &lt;uc:CircularProgressBar x:Name=&quot;CB&quot; StartupDelay=&quot;0&quot;
                                              RotationsPerMinute=&quot;20&quot;
                                              Height=&quot;25&quot; Foreground=&quot;White&quot;
                                              Margin=&quot;12&quot;/&gt;
      &lt;/StackPanel&gt;
  &lt;/Popup&gt;
  </code></pre>
  <p>How does one make the background on Popup transparent (or any color)?</p>