Dart APIunself_componentUnselfSliverNavigationBaropaque opaque property Null safety bool opaque Implementation bool get opaque => backgroundColor?.alpha == 0xFF; unself_component unself_component UnselfSliverNavigationBar opaque property UnselfSliverNavigationBar class Constructors UnselfSliverNavigationBar Properties automaticallyImplyLeading automaticallyImplyTitle backgroundColor border brightness hashCode heroTag key largeTitle leading middle opaque padding previousPageTitle runtimeType stretch trailing transitionBetweenRoutes Methods createElement createState debugDescribeChildren debugFillProperties noSuchMethod toDiagnosticsNode toString toStringDeep toStringShallow toStringShort Operators operator ==