title: Vertical Scroll in stackpanel
body: <p>I am trying to get a scroll bar to be placed on a stack panel.  The scroll bar displays but will not allow for the user to move the scroll bar at all. Is there something wrong with my XMAL or is there more to it?</p>
  
  <pre><code>&lt;GroupBox HorizontalAlignment="Left" Margin="268,8,0,0" VerticalAlignment="Top" Width="505.881" Height="352.653" Header="Metrics"&gt;
  &lt;Grid&gt;
      &lt;ScrollViewer&gt;
          &lt;StackPanel&gt;
                &lt;/StackPanel&gt;
            &lt;/ScrollViewer&gt;
        &lt;/Grid&gt;
  &lt;/GroupBox&gt;
  </code></pre>
  
  <p>The content of the stack panel is expanders with data contained with in them.</p>