title: How can I give a WPF element a rectangular flat 3D border?
body: <p>I would like to create a rectangular 'flat 3D' look for one of my control templates.  In it's most simple version this means having a line at the bottom that is darker than that at the top, and maybe some variation between the left and right lines too.</p>
  
  <p>A more complex version would allow me to provide on or more brushes so that gradients could be applied.</p>
  
  <p>The default <code>&lt;Border&gt;</code> element in WPF lets you specify a different thickness per edge, but I can't find a way to specify multiple brushes.</p>
  
  <p>So, how can I produce the effect I want as simply as possible?</p>
  
  <p><strong>EDIT</strong> it's been suggested that I post an example of how I want to use this.  Personally I'd be happy to have a style or a user control.  The user control might be used thus:</p>
  
  <pre><code>&lt;FourSidedBorder LeftSideBrush="#00f" RightSideBrush="#0f0" ... /&gt;
  </code></pre>
  
  <p>Or perhaps even simpler:</p>
  
  <pre><code>&lt;FourSidedBorder BorderBrush="#00f,#0f0,#f00,#fff"
                   BorderThickness="1,2,3,4" ... /&gt;
  </code></pre>
  
  <p>These are just ideas.  Any sensible, concise solution is welcome.</p>