ScrollableWidgetBuilder typedef
The signature of a method that provides a BuildContext and ScrollController for building a widget that may overflow the draggable Axis of the containing area.
This builder is used when a widget is expected to have a scrollable child widget, and a vertical gesture needs to trigger scrolling and some other behavior during that same gesture.
For example, users of DraggableScrollableSheet should apply the scrollController
to a ScrollView subclass, such as a SingleChildScrollView, ListView or
GridView, to have the whole sheet be draggable.
Implementation
typedef ScrollableWidgetBuilder =
Widget Function(BuildContext context, ScrollController scrollController);