title: CheckBox, action event
body: <p>I need to add a <code>Check box</code>, and when the user <code>checks</code> on it (as in changes the value <code>check/uncheck</code>) to print a <code>console.log</code> statement. So far i was able to display the check box, but unable to access its check event.</p>
  
  <pre><code>{
      xtype: 'checkboxgroup',
      columns: 1,
  
      listeners: {
          change: function (this, newValue, oldValue, eOpts) {
              console.log('change');
              console.log(newValue);
          }
      },
      items: [{
          boxLabel: 'Cars',
          name: 'chk1',
          inputValue: '1'
      }]
  }
  </code></pre>