Add test for opening lists in buttongroups

Change-Id: I60e1dcb31060e2cad43354e976fe12aad52f07ae
diff --git a/dev/js/src/buttongroup.js b/dev/js/src/buttongroup.js
index f7acfb7..b4d7813 100644
--- a/dev/js/src/buttongroup.js
+++ b/dev/js/src/buttongroup.js
@@ -84,6 +84,7 @@
      * 
      * Returns the list object.
      */
+    // TODO: Support icons by switching to a data object (see add())
     addList : function (title, classes, itemClass = defaultItemClass) {
       var list = treeMenuClass.create([], itemClass);
       this.add(title, classes, function (e) {