Index: branches/RC/core/units/general/helpers/priority_helper.php
===================================================================
diff -u -N -r11610 -r11668
--- branches/RC/core/units/general/helpers/priority_helper.php	(.../priority_helper.php)	(revision 11610)
+++ branches/RC/core/units/general/helpers/priority_helper.php	(.../priority_helper.php)	(revision 11668)
@@ -64,15 +64,23 @@
 		 */
 		function updatePriorities(&$event, $changes, $new_ids, $constrain = '')
 		{
+			if (!$changes) {
+				// no changes to process
+				return Array ();
+			}
+			list ($id, $pair) = each($changes);
+
+			if (!$id && !array_key_exists('parent', $pair)) {
+				// adding new item without constrain -> priority stays the same
+				return Array ($id);
+			}
+
 			$id_field = $this->Application->getUnitOption($event->Prefix, 'IDField');
 			$table_name = $this->Application->getUnitOption($event->Prefix, 'TableName');
 
+			$ids = array();
 			$not_processed = array_keys($changes);
-			if(!$not_processed || !getArrayValue($not_processed, 0)) {
-				return $not_processed;
-			}
 
-			$ids = array();
 			foreach ($changes as $id => $pair) {
 				array_push($ids, $id);
 				$constrain = isset($pair['parent']) ? 'ParentId = '.$pair['parent'].' AND ' : '';