anchor.diff:  const Duration _kDropDownMenuDuration = const Duration(milliseconds: 300);
   const double _kMenuItemHeight = 48.0;
   const EdgeInsets _kMenuVerticalPadding = const EdgeInsets.symmetric(vertical: 8.0);
  -const EdgeInsets _kMenuHorizontalPadding = const EdgeInsets.symmetric(horizontal: 36.0);
  +const EdgeInsets _kMenuHorizontalPadding = const EdgeInsets.symmetric(horizontal: 4.0);
   const double _kBaselineOffsetFromBottom = 20.0;
   const double _kBottomBorderHeight = 2.0;
   const Border _kDropDownUnderline = const Border(bottom: const BorderSide(color: const Color(0xFFBDBDBD), width: _kBottomBorderHeight));
  
positive.code: }
  
  class _DropDownButtonState<T> extends State<DropDownButton<T>> {
    final GlobalKey _itemKey = new GlobalKey(debugLabel: 'DropDownButton item key');
  
    @override
    void initState() {
      super.initState();
  
negative.code: 
    void _handleTap() {
      assert(_currentRoute == null);
      final RenderBox itemBox = context.findRenderObject();
      final Rect itemRect = itemBox.localToGlobal(Point.origin) & itemBox.size;
      final Completer<_DropDownRouteResult<T>> completer = new Completer<_DropDownRouteResult<T>>();
      _currentRoute = new _DropDownRoute<T>(
  