title: WPF error message: Partial declaration must not specify different base classes
body: <p>Why do I have this error message for a UserControl:</p>
  
  <blockquote>
    <p>Partial declaration of
    MyNamespace.MyUserControl must not
    specify different base classes</p>
  </blockquote>
  
  <p>Just because I inherited from another UserControl class I created in another namespace whereas this other namespace is referenced in the XAML as</p>
  
  <pre><code>xmlns:my="clr-namespace:ReferedNamespace;assembly=ReferedNamespace"
  </code></pre>