title: Changing toolbar button text on menu item selection EXTJS
body: <p>I have a grid with a toolbar  as given below</p>
  
  <pre><code>{
      xtype: 'tbbutton',
      text: 'Button',
      menu: [{
      text: 'Better'
      },{
          text: 'Good'
      },{
          text: 'Best'
      }]
  }
  </code></pre>
  
  <p>I want to write handler such that when I choose 'Good' the button text should change from 'Button' to 'Good'</p>
  
  <p>I am able to access text property in the handler</p>
  
  <p>Please help me..</p>