title: How to add title (like group header) in the telerik's radlistbox
body: <p>Code:</p>
  
  <pre><code>&lt;telerik:RadListBox x:Name="testStates"&gt;
  
  &lt;/telerik:RadListBox&gt;
  </code></pre>
  
  <p>I searched and not found a proper way to add a header / title in the radlistbox.</p>
  
  <p>How to add title / header (<em>like group header in asp.net ajax telerik control radlistbox</em>) in the <strong>telerik's radlistbox in wpf</strong> ?</p>
  
  <p>Can we achieve the solution by any other way if we can't able to do it in a recommended way?</p>