title: Get bottom-bar from panel extjs 4
body: <p>i have this panel with bbar:</p>
  
  <pre><code>panelModellazioneMS = new Ext.Panel({
     anchor: '100% 95%',
     layout: 'card',
     border: false,
     padding: '5 5 0 5',
     bbar: [ 
       {
      id: 'move-prevMS',
      text: 'Indietro',
      handler: function(btn) {..}
       }  ]
  });
  </code></pre>
  
  <p>I would get the bbar of this panel in an extern function to disable. how can I do?</p>