##  *** initialize the session with session_start();
##  *** default exporting directory (requires write permissions): tmp/export/ 
/// $exporting_option = true;
/// $export_all = false;
/// $dgrid->AllowExporting($exporting_option, $export_all);
/// $exporting_types = array("csv"=>"true", "xls"=>"true", "pdf"=>"true", "xml"=>"true");
/// $dgrid->AllowExportingTypes($exporting_types);