ReorderableList and SliverReorderableList contain an EdgeDraggingAutoScroller that advances the scroll position when dragging an item at the edge of the viewport.

A customer has requested to be able to configure this behavior, specifically to adjust the speed. I think this would be the EdgeDraggingAutoScroller.velocityScalar. This could be added as a property that is provided to the internal EdgeDraggingAutoScroller