title: Silverlight three state checkbox implementation via two states
body: <p>I need to handle three state checkbox in the following manner based on the first value:</p>
  
  <ul>
  <li><p>If checkbox in a checked state then It can be only unchecked.</p></li>
  <li><p>If checkbox in a uncheck state then it can be only checked.</p></li>
  <li><p>if checkbox in a middle state then it can be only checked.</p></li>
  </ul>
  
  <p>Can you please suggest on how this can be implemented?</p>