title: Referencing an item in a VirtualizingStackPanel
body: <p>I'm playing with the "Grid Application," which is a C++ Metro app template provided by VS11. The main display is a collection of items displayed in a VirtualizingStackPanel: </p>
  
  <pre><code>&lt;ScrollViewer x:name="itemGridScrollViewer"&gt;
    &lt;GridView x:name="itemGridView"&gt;
      &lt;GridView.ItemsPanel&gt;
        &lt;ItemsPanelTemplate&gt;
          &lt;VirtualizingStackPanel /&gt;
        &lt;/ItemsPanelTemplate&gt; 
      &lt;/GridView.ItemsPanel&gt;
    &lt;/GridView&gt;
  &lt;/ScrollViewer&gt;
  </code></pre>
  
  <p>The actual items are displayed using the Standard250x250ItemTemplate data template defined in StandardStyles.xaml. One of the display elements of this is a graphic.</p>
  
  <p>I'm trying to understand how to reference a specific item so that I can change the graphic at runtime. The ScrollViewer and the GridView have objects associated with them, so I can get to those, but I don't see how to get from there to the individual items.</p>
  
  <p>All this stuff is completely new to me, so be gentle. :)</p>