Index: gc_core/js/lang_core/gc_engine.js
==================================================================
--- gc_core/js/lang_core/gc_engine.js
+++ gc_core/js/lang_core/gc_engine.js
@@ -278,11 +278,11 @@
 
     reactivateRule: function (sRuleId) {
         _aIgnoredRules.delete(sRuleId);
     },
 
-    listRules: function (sFilter=null) {
+    listRules: function* (sFilter=null) {
         // generator: returns tuple (sOption, sLineId, sRuleId)
         try {
             for (let [sOption, lRuleGroup] of this._getRules(true)) {
                 for (let [x1, x2, sLineId, sRuleId, x3, x4] of lRuleGroup) {
                     if (!sFilter || sRuleId.test(sFilter)) {