anchor.diff:      this.itemRenderer = defaultItemRenderer;
     }
   
  +  @HostBinding('attr.aria-selected')
  +  @override
  +  bool get isSelected => super.isSelected;
  +
  +  @HostListener('mousedown')
     void preventTextSelectionIfShiftKey(MouseEvent e) {
       if (e.shiftKey) e.preventDefault();
     }
  
positive.code: /// This should only be used in select dropdowns.
  @Component(
    selector: 'material-select-dropdown-item',
    host: const {
      '[class.disabled]': 'disabled',
      '[class.hidden]': 'isHidden',
      '[class.active]': 'active',
      '[class.selected]': 'isSelected',
      '[class.multiselect]': 'supportsMultiSelect',
      '(click)': r'handleClick($event)',
      '(keypress)': r'handleKeyPress($event)',
      '(mousedown)': r'preventTextSelectionIfShiftKey($event)',
      '(mouseenter)': 'onMouseEnter()',
      '(mouseleave)': 'onMouseLeave()',
      '[attr.aria-selected]': 'isSelected',
      '[attr.aria-disabled]': 'disabledStr',
      '[attr.id]': 'id',
    },
    providers: const [
      const Provider(SelectionItem,
          useExisting: MaterialSelectDropdownItemComponent),
  
negative.code:   String _id;
  
    /// The id of the element.
    @HostBinding('attr.id')
    String get id => _id ?? _generatedId;
  
    @Input()
    set id(String id) {
      _id = id;
  