anchor.diff:  
     @override
     set options(SelectionOptions<T> newOptions) {
  +    _changeDetector.markForCheck();
       super.options = newOptions;
   
       _updateActiveModel();
  
positive.code:   /// Whether the dropdown is visible.
    @override
    set visible(bool value) {
      super.visible = value;
      resetEnteredKeys();
      if (value) {
  
negative.code: 
      _optionsListener?.cancel();
      _optionsListener = options?.stream?.listen((_) {
        _changeDetector.markForCheck();
        _updateActiveModel();
        _setInitialActiveItem();
      });
  