Index: branches/unlabeled/unlabeled-1.27.2/core/units/categories/categories_event_handler.php
===================================================================
diff -u -N -r7743 -r7744
--- branches/unlabeled/unlabeled-1.27.2/core/units/categories/categories_event_handler.php	(.../categories_event_handler.php)	(revision 7743)
+++ branches/unlabeled/unlabeled-1.27.2/core/units/categories/categories_event_handler.php	(.../categories_event_handler.php)	(revision 7744)
@@ -100,7 +100,7 @@
 		// hide categories with status = 4 (system categories)
 		$object->addFilter('system_categories', '%1$s.Status <> 4');
 
-		if ( $event->getEventParam('parent_cat_id') ) {
+		if ($event->getEventParam('parent_cat_id') !== false) {
 			$parent_cat_id = $event->getEventParam('parent_cat_id');
 
 			if ($parent_cat_id == 'Root') {