REVO 2.2.2-pl inherit parent template

<?php
if ($modx->event->name == 'OnDocFormRender' && $mode == modSystemEvent::MODE_NEW) {
  $parent_id = $modx->getOption('parent', $_REQUEST, 0);
  if ($parent_id) {
    $parent = $modx->getObject('modResource', $parent_id);
    if ($parent) {
      $template_id = $parent->get('template');
      if (isset($modx->controller)) {
	$modx->controller->setProperty('template', $template_id);
      } else { // modX < 2.2.0
	$_REQUEST['template'] = $template_id;
      }
    }
  }
}