title: How can I find a root node in TreeView
body: <p>I have a TreeView in my Windows application. Tn this TreeView, the user can add some root nodes and also some sub nodes for these root nodes and also some sub nodes for these sub nodes and so on ...</p>
  
  <p>For example:</p>
  
  <pre><code>Root1
       A
         B
           C
           D
            E  
  Root2
       F
        G
  .
  .
  .
  </code></pre>
  
  <p>Now my question is that if I am at node 'E' what is the best way to find its first root node ('Root1')?</p>