Dart APIunself_componentUnselfNavigationBarbackgroundColor backgroundColor property Null safety Color? backgroundColor final Implementation final Color? backgroundColor; unself_component unself_component UnselfNavigationBar backgroundColor property UnselfNavigationBar class Constructors UnselfNavigationBar Properties automaticallyImplyLeading automaticallyImplyMiddle backgroundColor border brightness hashCode heroTag key leading middle padding preferredSize previousPageTitle runtimeType trailing transitionBetweenRoutes Methods createElement createState debugDescribeChildren debugFillProperties noSuchMethod shouldFullyObstruct toDiagnosticsNode toString toStringDeep toStringShallow toStringShort Operators operator ==