title: How to use PathFigure from resources in PathGeometry?
body: <p>I wonder whether is there any way to use a <code>PathFigure</code> from resources in <code>PathGeometry</code> element in xaml. Let's say I have a ResourceDictionary and a two <code>PathFigure</code> objects inside it with the 'x:Key' attributes equal to "Figure1" and "Figure2" respectively. 
  My goal is to create a <code>PathGeometry</code> with <code>Figures</code> property filled with a collection containing Figure1 and Figure2. I can do it so easily with a code behind file, however I would like to know is there any way to do it with xaml only.</p>
  
  <pre><code>&lt;PathFigure IsClosed="True" StartPoint="2,9" x:Key="Figure1"&gt;
      &lt;ArcSegment Point="15,9" Size="6.5, 2"/&gt;
      &lt;LineSegment Point="15,12"/&gt;
      &lt;ArcSegment Point="2,12" Size="6.5, 2"/&gt;
  &lt;/PathFigure&gt;
  
  &lt;PathFigure IsClosed="True" StartPoint="10,7" x:Key="Figure2"&gt;
      &lt;LineSegment Point="10, 2"/&gt;
      &lt;LineSegment Point="13,2"/&gt;
      &lt;LineSegment Point="13,7"/&gt;
      &lt;ArcSegment Point="10,7" Size="2,2" IsLargeArc="True"/&gt;
  &lt;/PathFigure&gt;
  </code></pre>
  
  <p>I can create now a <code>PathGeometry</code> :</p>
  
  <pre><code>&lt;PathGeometry FillRule="Nonzero" x:Key="1"&gt;
      &lt;PathFigureCollection&gt;
          //Here I want to put Figure1 and Figure2
      &lt;/PathFigureCollection&gt;
  &lt;/PathGeometry&gt;
  </code></pre>
  
  <p>I think I can write some kind of <code>MarkupExtension</code> to do the following, but I am looking for the best way.
  Thanks for your advices.</p>