title: page.DataContext not inherited from parent Frame?
body: <p>I have a Page <code>page</code> in a Frame <code>frame</code>, with <code>frame.DataContext = "foo"</code>.</p>
  
  <ul>
  <li><code>(page.Parent as Frame).DataContext</code> is <code>"foo"</code>. <strong>ok</strong></li>
  <li>BindingExpression for <code>page.DataContext</code> is <code>null</code> (also forced with ClearValue). <strong>ok</strong></li>
  <li><code>page.DataContext</code> is <code>null</code>. <strong>but I expected "foo"!</strong></li>
  </ul>
  
  <p>Why isn't the DataContext inherited? As far as I <a href="http://social.msdn.microsoft.com/forums/en-US/wpf/thread/9d96e53d-94cc-4089-a51d-944d3a362870/" rel="noreferrer">understand</a> the Frame <em>sandboxes</em> the content. But I couldn't find any documentation of this behavior - can anyone point me to a place where this is mentioned?</p>