title: ExtJS setTitle() doesn't update the panel title
body: <p>I have a panel as follows:</p>
  
  <pre><code>Ext.define('TestPanel', {
    extend: 'Ext.panel.Panel',
    alias: 'widget.testPanel',
  id: 'testerPanel',
  title: 'oldTilte',
  //other code
  });
  </code></pre>
  
  <p>I have a controller of a different view where I wish to update the panel title:</p>
  
  <pre><code>var grid = Ext.getCmp('testerPanel');
  grid.setTitle('newTitle'); //doesn't update the title
  
  //tried with including ref or view in the controller
  this.getTestPanel().setTitle('newTitle'); //this didn't update it either
  </code></pre>
  
  <p>How can I update the panel title? Also for both above tries, if I print the <code>console.info(grid)</code> or <code>console.info(this.getTestPanel())</code>, I always see the updated title in the console output but the UI itself remains unchanged</p>