title: Jqgrid: getRowData fails with error unable to get property name of undefined
body: <p>I am trying to call this method on a grouped jqgrid. My call to getGridParam does work but it fails on getRowData. </p>
  
  <pre><code>var selRow = myGrid.jqGrid('getGridParam', 'selrow');
  myGrid.getRowData(selRow);
  </code></pre>