title: Adding Unselectable controls to RibbonMenuButton
body: <p>I am working on a WPF project and I started developing the <code>Ribbon</code> area. I just put a <code>RibbonMenuButton</code> and added three <code>RibbonTextBox</code> inside of it. I want these TextBoxes to retrieve some data from the user. Everything is fine so far.</p>
  
  <pre><code>&lt;rb:RibbonMenuButton LargeImageSource="/image.png" Label="Settings"   &gt;
  
      &lt;rb:RibbonTextBox Label="Field 01:" Text="{Binding Field01 }" /&gt;
      &lt;rb:RibbonTextBox Label="Field 02:" Text="{Binding Field02 }" /&gt;
      &lt;rb:RibbonTextBox Label="Field 03:" Text="{Binding Field03 }" /&gt;
  
  &lt;/rb:RibbonMenuButton&gt;
  </code></pre>
  
  <p>My problem is that <strong>the <code>RibbonTextBox</code> becomes a menu item, i.e. I can click it and select it.</strong> </p>
  
  <p>But I want to avoid this behavior, I just want to have an <strong>"unselectable"</strong> <code>RibbonTextBox</code>.</p>
  
  <p><strong>Is there a way to achieve that?</strong></p>
  
  <p>Thank you in advance. </p>