title: Hidden expander overlap below it
body: <p>I have little problem. </p>
  
  <p>In my WPF appliaciton i have expander</p>
  
  <pre><code> &gt;&gt;some content 
            &lt;Expander ExpandDirection="Right" Header="" Margin="341,6,-6,0" BorderBrush="{x:Null}" Foreground="Black" Canvas.ZIndex="-1"&gt;
                  &lt;StackPanel Background="#FFE2E2E2" Margin="-28,30,-4,-2" Width="175" Opacity=".8"&gt;
  
                          &gt;&gt;some content&lt;&lt;
  
                  &lt;/StackPanel&gt;
              &lt;/Expander&gt;
  
          &lt;/Grid&gt;
      &lt;/Window&gt;
  </code></pre>
  
  <p>When you eject it covers the original content, its good, but content is invisibly covered if are expander is hidden too and content under it can not use.</p>
  
  <p>My think is: If expander is hidden - it have z-index: -1 and normal content can use, if I eject it - expander have z-index:1
  but I do not know how to do it, thank you for reply.</p>