title: How to extend Windows.UI.Xaml.Shapes.Shape in Win Store App (8.1)?
body: <p>After several hours of research on how to extend the <code>Windows.UI.Xaml.Shapes.Shape</code> class, I need to ask you guys if anybody can help me.</p>
  
  <p>Basically I need an ordinary rectangle (since its sealed, I cannot extend the <code>Windows.UI.Xaml.Shapes.Rectangle</code> class) and add some members to it. So I need a class which draws a ordinary rectangle with additional members.</p>