title: Canvas doesn't refresh unless the WPF Window is moved
body: <p>I have a simple WPF Window with a Canvas on it and the Canvas has a Path object with a GeometryGroup inside the Path:</p>
  
  <p></p>
  
  <pre><code>&lt;Path
        Stroke="Red"
        StrokeThickness="3"&gt;
      &lt;Path.Data&gt;
          &lt;GeometryGroup Children="{Binding Elements}" /&gt;
      &lt;/Path.Data&gt;
  &lt;/Path&gt;
  </code></pre>
  
  <p></p>
  
  <p>So I initialize the Elements collection before the <code>InitializeComponent()</code> call and it shows up correctly. After that using a <code>System.Timers.Timer</code> I update the existing shape's points so they move. This works. But the problem is I only see the Canvas updating its result when the WPF Window is moved by a mouse. If I leave it there, then the last image just hangs there but the points are updated.</p>
  
  <p>I can see this when I start moving the WPF Window again and the Shapes jump to their latest location.</p>
  
  <p>Any ideas on how to fix this and why it's doing it?</p>