title: Ext js row expander plugin row body template not rendered when parent grid panel refreshes
body: <p>I have grid panel with row expander plugin. When the user expands the row, I am rendering a nested grid dynamically from my controller. This all works fine, but when there's any event (eg. paging tool bar navigation), that refreshes the parent grid, the previously rendered nested grid won't be rendered any more. Is there a way to maintain the previously rendered nested grid even after the parent grid refreshes?</p>
  
  <p>Below is my code. </p>
  
  <pre><code>// Row expander plugin
  ...
  plugins: [
      {
          ptype: 'rowexpander',
          expandOnDblClick: false,
          selectRowOnExpand: false,
          tooltip : 'Activities',
          rowBodyTpl : ['&lt;div id="myrow-{id}"&gt;&lt;/div&gt;']
      }
  ]
  
  // Controller function that adds nested grid in rowBodyTpl: ['&lt;div id="myrow-{id}"&gt;&lt;/div&gt;'] when user expand a specific row
  onRowExpanded: function(rowNode, record, expandbody) {
      var rowContainerId = "myrow-" + record.id;
      var nestedGridId = "myGrid-" + record.id;
  
      var check = Ext.getCmp(nestedGridId);
      if (!check) {
          console.log('Element Created');
          var taskGrid = Ext.create('APP.view.main.taskGrid', {
              id: nestedGridId
          });
          taskGrid.render(rowContainerId);
      }
  }
  </code></pre>