anchor.diff:    _DatePickerMode _mode = _DatePickerMode.day;
     GlobalKey _pickerKey = new GlobalKey();
   
  +  void _vibrate() {
  +    switch (Theme.of(context).platform) {
  +      case TargetPlatform.android:
  +      case TargetPlatform.fuchsia:
  +        HapticFeedback.vibrate();
  +        break;
  +      case TargetPlatform.iOS:
  +        break;
  +    }
  +  }
  +
     void _handleModeChanged(_DatePickerMode mode) {
  -    if (_vibrate)
  -      HapticFeedback.vibrate();
  +    _vibrate();
       setState(() {
         _mode = mode;
       });
     }
   
     void _handleYearChanged(DateTime value) {
  -    if (_vibrate)
  -      HapticFeedback.vibrate();
  +    _vibrate();
       setState(() {
         _mode = _DatePickerMode.day;
         _selectedDate = value;
  
positive.code: 
    @override
    Widget build(BuildContext context) {
      switch (Theme.of(context).platform) {
        case TargetPlatform.android:
        case TargetPlatform.fuchsia:
          _vibrate = true;
          break;
        case TargetPlatform.iOS:
          _vibrate = false;
          break;
      }
      Widget picker = new Flexible(
        child: new SizedBox(
          height: _kMaxDayPickerHeight,
  
negative.code: }
  
  class _DatePickerDialogState extends State<_DatePickerDialog> {
    @override
    void initState() {
      super.initState();
  