title: Binding values to panel title
body: <p>I have a problem when I am binding values to a panel title.</p>
  
  <p>My code basically looks like this :</p>
  
  <pre><code>Ext.define('serviceteamWorkflow.view.core.ServiceteamWorkflow', {
      extend: 'Ext.Panel',
      bind: {
          title: 'First Name : {firstName} Last Name : {lastName}'
      },
  
  })
  </code></pre>
  
  <p>The problem is that nothing shows in the title when one of the bound values is null or undefined. Ie. If one of the bound values is invalid then the whole thing won't show.</p>
  
  <p>I would like to just show nothing if the bound value is invalid. ie :</p>
  
  <p><strong>First Name : Last Name : Doe</strong></p>
  
  <p>Is there a way around this?</p>