title: Round a arbitrary content control
body: <p>I have an Esri ArcGis map control which I want to round around the edges. I am also using Prism4.0/MEF and SL4.</p>
  
  <p>I tried to place it in a border, but that doesn't work (the Esri control is loaded into the MapRegion, in another module):</p>
  
  <pre><code>&lt;Border Grid.Row="2"
                  Margin="2"
                  CornerRadius="25"&gt;
              &lt;ContentControl
                  prism:RegionManager.RegionName="MapRegion"
                  VerticalContentAlignment="Stretch"
                  HorizontalContentAlignment="Stretch"&gt;
              &lt;/ContentControl&gt;
          &lt;/Border&gt;
  </code></pre>