title: Deriving from UserControl in Silverlight
body: <p>In Silverlight 2 I have the following class declaration for a control:</p>
  
  <pre><code>public partial class ClassX : UserControl
  </code></pre>
  
  <p>I wish to replace UserControl with ClassXBase which derives from UserControl but I'm getting the reasonable error "Partial declarations of 'ClassX' must not specify different base classes"</p>
  
  <p>However, I'm unable to find the other partial class to replace its base class. Any idea where this other partial class is or how I do this?</p>