code: function(dataIndex){
          var view = this.view,
              header = view.headerCt.down('gridcolumn[dataIndex=' + dataIndex + ']'),
              menu = view.headerCt.getMenu();
  
          return header ? menu.down('menuitem[headerId='+ header.id +']') : null;
      }
docs: Gets the related menu item for a dataIndex
  @private
  @return {Ext.grid.header.Container} The header