title: WPF HierarchicalDataTemplate
body: <p>Could anyone explain how HierarchicalDataTemplate works</p>
  
  <ul>
  <li>What Controls supports HierarchicalDataTemplate?</li>
  <li>What does a control need to support HierarchicalDataTemplate?</li>
  </ul>
  
  <p><strong>UPDATE</strong></p>
  
  <ul>
  <li>What causes the TreeView to render
  the parent and child nodes when the
  same HierarchicalDataTemplate in a
  HeaderedItemsControl only causes the
  parent to be rendered?</li>
  </ul>