title: WPF Animation of border width
body: <p>I've got a dockpanel on my ui as follows;</p>
  
  <pre><code>&lt;DockPanel&gt;
      &lt;Border DockPanel.Dock="Top"&gt;Header&lt;/Border&gt;
      &lt;Border DockPanel.Dock="Bottom"&gt;My footer&lt;/Border&gt;
      &lt;Border DockPanel.Dock="Left"&gt;Menu&lt;/Border&gt;
  
      &lt;Border&gt;Content&lt;/Border&gt;
   &lt;/DockPanel&gt;
  </code></pre>
  
  <p>What I want to do is to have a storyboard animation to show / hide the Menu on the left-hand side. I've got my border to increase the width when it has loaded but I want a way to close / reopen it. I need a button somewhere but I want this to trigger the animation in the border control rather than itself. Ideally I was thinking of something like the Toolbox / Server Explorer in visual studio.</p>
  
  <p>Does anyone have any pointers / examples for getting started?</p>
  
  <p>Thanks</p>