title: How to Bind to a Child's Background in Xaml?
body: <p>I'm able to bind to a child's Background if the child is explicitly named in ElementName:</p>
  
  <pre><code>&lt;TreeViewItem Header="Test" Background="{Binding ElementName=TestChild, Path=Background}"&gt;
     &lt;TextBox Name="TestChild" Text="Hello?" Background="{Binding SomeBinding}" /&gt;
  &lt;/TreeViewItem&gt;
  </code></pre>
  
  <p>I'd prefer to use relative position rather than specific names. Is it possible to bind to a child using relative? In this case it will always be the first child. The following DOESN'T work but seems like it should.</p>
  
  <pre><code>&lt;TreeViewItem Header="Test" Background="{Binding RelativeSource={RelativeSource Mode=Self}, Path=Children[0].Background}"&gt;
  </code></pre>