title: Adding listener to an editor grid panel
body: <p>There is an Editor grid panel.<br>
  I am trying to add a listener to the cell click event.  I have tried to do it in different ways:  </p>
  
  <pre><code>gridPanel.addListener('cellclick',myfunction);  
  </code></pre>
  
  <p>inside the grid:  </p>
  
  <pre><code>listeners: {
      cellclick: myfunction
  }
  </code></pre>
  
  <p>I have tried to do it in the selectionModel object.<br>
  None of them worked.<br>
  Where can be the problem?  </p>