minOverscrollLength property
The preferred smallest size the scrollbar thumb can shrink to when viewport is overscrolled.
When overscrolling, the size of the scrollbar's thumb may shrink to a smaller size than minOverscrollLength to fit in the available paint area (e.g., when minOverscrollLength is greater than ScrollMetrics.viewportDimension and mainAxisMargin combined).
Overscrolling can be made possible by setting the physics property
of the child Widget to a BouncingScrollPhysics, which is a special
ScrollPhysics that allows overscrolling.
The value is less than or equal to minThumbLength and greater than or equal to 0. When null, it will default to the value of minThumbLength.
Implementation
final double? minOverscrollLength;