flutter-sliver - 条子持久标头的折叠子项的问题

Question

下面是带有折叠子项和展开子项的 sliver 持久标头的代码。当滚动折叠的孩子不点击，而只是显示。是堆栈的问题，有没有办法解决它。我相信它来自 Stack，但我不知道如何绕过它。该类用于长条子持久标头，并且子项是折叠的子项和子项

class _SliverAppbarDelegate extends SliverPersistentHeaderDelegate {
  final double minHeight;
  final double maxHeight;
  final Widget child;
 // final Widget collapsedchild;
  bool shrink;
  ScrollPosition _position;

  _SliverAppbarDelegate({
    @required this.minHeight,
   // @required this.collapsedchild,
    @required this.maxHeight,
    @required this.child,
  });

 
  @override
  double get minExtent => minHeight;
  @override
  double get maxExtent => maxHeight;
   
  @override
  Widget build(
      BuildContext context, double shrinkOffset, bool overlapsContent) {
   
       
   
      return Stack(children: [
         Opacity(opacity: disappear(shrinkOffset), child: child),buildAppbar(shrinkOffset),
      ],
       
      
    );
    
  }
 // ignore: slash_for_doc_comments
  @override
  bool shouldRebuild(_SliverAppbarDelegate oldDelegate) {
    return 
    
    maxHeight != oldDelegate.maxHeight ||
        minHeight != oldDelegate.minHeight ||
        child != oldDelegate.child ;
      //  collapsedchild != oldDelegate.collapsedchild;
        
  }
    


  double appear(double shrinkOffset) => shrinkOffset / maxHeight;
  double disappear(double shrinkOffset) => 1 - shrinkOffset / maxHeight;
  
  Widget buildAppbar(double shrinkOffset) =>
      Opacity(opacity: appear(shrinkOffset), child: CalendarCarousel(weekFormat: true,));
}