title: Having issues capturing rowIndex in column renderer
body: <p>I’m attempting to check a box in a grid using the CheckBoxSelectionModel.<br>
  As the grid loads data from my store, how do I get the rowIndex of the row being loaded?  I would like to test the value of a particular column dataIndex, and based on the value I would like to select  the box at the beginning of the row.
  This code does not work, but this is what I’d like to do:</p>
  
  <pre><code>   columns:
  
              [
                      {dataIndex: 'de_sealed_doc', renderer: function(value,rowIndex,store,record){
  
                      console.log('rowIndex == '+rowIndex);
  
                      var sealedDocIndex = this.rowIndex;
  
                      //var gridModel = grid.getSelectionModel().select(2);
  
                      grid.getSelectionModel().select(sealedDocIndex);
  
                      //grid.getSelectionModel().selectAll();
  
                      console.log('sealedDocIndex --&gt; '+sealedDocIndex);
                      //console.log('gridModel--&gt; '+gridModel);
                      console.log('value--&gt; '+value);
  
  
  
                      },
  
                      hidden: true},
  
                      {header: 'Document #', dataIndex: 'de_seqno', width: 100},
                      {header: 'Docket Text', dataIndex: 'docketText', renderer: this.customRenderer, width: 1000},
                      {header: 'Document(s)', dataIndex: 'docsDisplay', width: 500}
  
              ],
  </code></pre>
  
  <p>Could someone please assist me with this?  If you need to see more of the code, so that it makes more sense, just let me know.</p>