title: WPF binding with PlacementTarget and RelativeSource
body: <p>Can you explain the following WPF code:</p>
  
  <pre><code>DataContext="{Binding Path=PlacementTarget,RelativeSource={x:Static RelativeSource.Self}}"&gt;
  </code></pre>
  
  <p>I find it extremely confusing. What is placement target and what is relative source?</p>