anchor.diff:      bool value,
       Color activeColor,
       Color inactiveColor,
  +    Decoration activeThumbDecoration,
  +    Decoration inactiveThumbDecoration,
       Color activeTrackColor,
       Color inactiveTrackColor,
       ValueChanged<bool> onChanged
  -  }) : super(
  -     value: value,
  -     activeColor: activeColor,
  -     inactiveColor: inactiveColor,
  -     onChanged: onChanged,
  -     minRadialReactionRadius: _kThumbRadius,
  -     size: const Size(_kSwitchWidth, _kSwitchHeight)
  -   ) {
  -    _activeTrackColor = activeTrackColor;
  -    _inactiveTrackColor = inactiveTrackColor;
  +  }) : _activeThumbDecoration = activeThumbDecoration,
  +       _inactiveThumbDecoration = inactiveThumbDecoration,
  +       _activeTrackColor = activeTrackColor,
  +       _inactiveTrackColor = inactiveTrackColor,
  +       super(
  +         value: value,
  +         activeColor: activeColor,
  +         inactiveColor: inactiveColor,
  +         onChanged: onChanged,
  +         minRadialReactionRadius: _kThumbRadius,
  +         size: const Size(_kSwitchWidth, _kSwitchHeight)
  +       ) {
       _drag = new HorizontalDragGestureRecognizer()
         ..onStart = _handleDragStart
         ..onUpdate = _handleDragUpdate
         ..onEnd = _handleDragEnd;
  +  }
  +
  +  Decoration get activeThumbDecoration => _activeThumbDecoration;
  +  Decoration _activeThumbDecoration;
  +  void set activeThumbDecoration(Decoration value) {
  +    if (value == _activeThumbDecoration)
  +      return;
  +    _activeThumbDecoration = value;
  +    markNeedsPaint();
  +  }
  +
  +  Decoration get inactiveThumbDecoration => _inactiveThumbDecoration;
  +  Decoration _inactiveThumbDecoration;
  +  void set inactiveThumbDecoration(Decoration value) {
  +    if (value == _inactiveThumbDecoration)
  +      return;
  +    _inactiveThumbDecoration = value;
  +    markNeedsPaint();
     }
   
     Color get activeTrackColor => _activeTrackColor;
  
positive.code:     this.value,
      this.activeColor,
      this.inactiveColor,
      this.activeTrackColor,
      this.inactiveTrackColor,
      this.onChanged
  
negative.code:     value: value,
      activeColor: activeColor,
      inactiveColor: inactiveColor,
      activeThumbDecoration: activeThumbDecoration,
      inactiveThumbDecoration: inactiveThumbDecoration,
      activeTrackColor: activeTrackColor,
      inactiveTrackColor: inactiveTrackColor,
      onChanged: onChanged
  