gistfile1.js

/*
 * Extends PanelRowExpander to show an edit panel in the expansion instead of an ExtTemplate.
 */
MyApp.MyRowExpander = function(config){
    Ext.apply(this, config);
    MyApp.MyRowExpander.superclass.constructor.call(this);
};

Ext.extend(MyApp.MyRowExpander, Ext.grid.PanelRowExpander, {

  createExpandingRowPanelItems: function( record, rowIndex ) {
    var p = new Ext.form.FormPanel({
      idSuffix: 'expand-'+record.id,
      border: false,
      height: Math.max(Ext.getCmp('Mysgridpanel').getInnerHeight() * 0.5, 150),
      hideTitles: true,
      html: 'My form!'
    });

    p.on('close', function() {
      this.collapseRow(rowIndex);
    }, this);
      
    return [p];
  }

});