如何在flutter中禁用除一个选中的子项之外的所有子项的点击事件？

class MyWidget extends StatefulWidget {
  @override
  _MyWidgetState createState() => _MyWidgetState();
}

class _MyWidgetState extends State<MyWidget> {
  int selectedIndex = -1;

  @override
  Widget build(BuildContext context) {
    return Column(
      children: [
        MyItem(
          index: 0,
          isSelected: selectedIndex == 0,
          onTap: () {
            setState(() {
              selectedIndex = 0;
            });
          },
        ),
        MyItem(
          index: 1,
          isSelected: selectedIndex == 1,
          onTap: () {
            setState(() {
              selectedIndex = 1;
            });
          },
        ),
        MyItem(
          index: 2,
          isSelected: selectedIndex == 2,
          onTap: () {
            setState(() {
              selectedIndex = 2;
            });
          },
        ),
      ],
    );
  }
}

class MyItem extends StatelessWidget {
  final int index;
  final bool isSelected;
  final VoidCallback onTap;

  MyItem({required this.index, required this.isSelected, required this.onTap});

  @override
  Widget build(BuildContext context) {
    return GestureDetector(
      onTap: isSelected ? null : onTap,
      child: Container(
        color: isSelected ? Colors.grey : Colors.white,
        child: Text('Item $index'),
      ),
    );
  }
}