anchor.diff:    String _ariaActiveDescendant;
   
     final ChangeDetectorRef _changeDetector;
  +
  +  bool _disabledChanged = false;
  +
  +  @override
  +  set disabled(bool value) {
  +    super.disabled = value;
  +    _disabledChanged = true;
  +  }
   
     MaterialDropdownSelectComponent(
         @Optional() IdGenerator idGenerator,
  
positive.code:   }
  
    @override
    ngOnChanges(Map<String, SimpleChange> changes) {
      if (changes.containsKey('disabled') && disabled) {
        close();
      }
    }
  
    @override
    ngOnDestroy() {
      _optionsListener?.cancel();
      _selectionListener?.cancel();
    }
  
negative.code:         KeyboardHandlerMixin,
          ActivateItemOnKeyPressMixin<T>,
          ShiftClickSelectionMixin<T>
      implements PopupSizeProvider, AfterChanges, OnDestroy {
    /// Function for use by NgFor for optionGroup.
    ///
    /// Avoids recreating the DOM for the optionGroup.
  