update assets

assets/admin/js/SelectBox.js

@@ -41,6 +41,10 @@
             }
             SelectBox.redisplay(id);
         },
+        get_hidden_node_count(id) {
+            const cache = SelectBox.cache[id] || [];
+            return cache.filter(node => node.displayed === 0).length;
+        },
         delete_from_cache: function(id, value) {
             let delete_index = null;
             const cache = SelectBox.cache[id];