startCurtain property
The Decoration to display at the start of the scrollable child when there is content behind/underneath it. (When the start of the scrollable has been scrolled away from.)
Left null, an empty decoration is provided.
Consider a const BoxDecoration(. . .).
The start value in sensitivity correlates to this curtain's
tolerance to the minimum scrollable extent of its child.
Implementation
final Decoration? startCurtain;