title: Extjs 4.x - CheckboxModel to get checked and unchecked value
body: <p>I have used check box model in the grid panel. When i checked the check box i am the checked column value. Now what i need is when i unchecked i need to get that same unchecked value.</p>
  
  <pre><code>var selModel = Ext.create('Ext.selection.CheckboxModel', {
      checkOnly: true,
      listeners: {
          selectionchange: function(model, records) {
              if (records[0]) {
                  id = records[0].get('id');
                  alert(id);
              }
          }
      }
  });
  </code></pre>
  
  <p>Thanks in advance.</p>
  
  <p>Regards,</p>
  
  <p>Riyaz</p>