I would like to create a scrollable list that has borders at the top and at the button but only when the list’s content “overflows” in the corresponding direction. So:

• when the list fits entirely into the available space: no borders.
• when the list doesn’t fit and
  • overflows at the bottom: a bottom border is shown.
  • overflows at the top: a bottom border is shown.
  • overflows at the top and the bottom: both a top and a bottom border are shown.

I tried something like that:

build() {
  bool showTop = scrollController.offset > 0;
  bool showBottom = scrollController.position.minScrollExtent != scrollViewController.position.maxScrollExtent;

  return Stack(
    children: [
      ListView(controller: scrollController, builder: (){
        // build children
      }),
      if(showTop) buildTop(),
      if(showBottom) buildBottom(),
    ]
  );
}

But I receive a “ScrollController not attached to any scroll views.” exception. Which makes sense but also makes me wonder how I could achieve the desired effect.