title: Extend an existing struct in C# to add operators
body: <p>I want to extend the .NET's built-in <code>Color</code> struct to add new operators like <code>+</code> or <code>-</code>.<br>
  I will use them like:</p>
  
  <pre><code>Color c1 = Color.FromName("Red");
  Color c2 = Color.FromName("Blue");
  Color result = c2 - c1;
  </code></pre>
  
  <p>Is it possible? if yes, how?</p>