The default ScrollBehavior for the application.
ScrollBehaviors describe how Scrollable widgets behave. Providing a ScrollBehavior can set the default ScrollPhysics across an application, and manage Scrollable decorations like Scrollbars and GlowingOverscrollIndicators.
When null, defaults to MaterialScrollBehavior.
- ScrollConfiguration, which controls how Scrollable widgets behave in a subtree.
final ScrollBehavior? scrollBehavior;