title: WPF Triggering by ancestral property
body: <p>I would like to use trigger the trigger, but i need to select the ancestor's property, for example:</p>
  
  <pre><code>&lt;Trigger Property="State" Value="Expanded"&gt;
     &lt;Setter Property="Background" Value="Red" /&gt;
  &lt;/Trigger&gt;
  </code></pre>
  
  <p>Only that the State property need to be the property of an unknown ancestor by a known Type 
  and if could not be found then trigger would never execute.</p>
  
  <p>So my question is how can I find the ancestor to get the property to use in the trigger?</p>
  
  <p>Hope I made myself clear.
  Thank you in advance.</p>