title: Ext Js 4 - CellModel Multi Select not working?
body: <p>I am trying to implement the <code>Ext.selection.CellModel</code> with <code>mode: 'MULTI'</code> however the grid still only allows one cell to be selected at a time?<br>
  Below is some sample code:</p>
  
  <pre><code>var cellmodel = new Ext.selection.CellModel({
      mode: 'MULTI'
  });
  
   var grid = new Ext.grid.Panel({
      store: store,
      selModel: cellmodel,
      multiSelect: true,
      ....
   });
  </code></pre>
  
  <p>Am I missing something or is this a bug within the Ext code itself?</p>