public function buildTabIndexMap(container:DisplayObjectContainer):Object {
        var items:Object = {};
        var child:DisplayObject;
        var i:int;

        for (i = 0; i < container.numChildren; i++) {
            child = container.getChildAt(i);
            if (child is InteractiveObject) {
                var ti:int;
                ti = InteractiveObject(child).tabIndex;
                if (ti >= 0)
                    items[ti] = child;
            }

            if (child is DisplayObjectContainer) {
                var subitems:Object = buildTabIndexMap(child);
                // merge subitems into items
                for (var j:int in subitems) {
                    items[j] = subitems[j];
                }
            }
        }

        return items;
    }