Creating another Navigator right inside of MaterialApp

sub_navigator.dart

Creating another Navigator right inside of MaterialApp - some kind of a second 'sub-root' navigator.

Now you will be able to choose between 2 layers of Navigator depending on your needs.

Navigator.of(context, rootNavigator: true) will return the top-level Navigator - use it for your Flushbar or any other modal popups that you want to keep persistent above all screens.

Navigator.of(context), where rootNavigator is false by default. Use it to get the 'sub-root' Navigator to display new screens / pages.

e.g. placing another Navigator right in the MaterialApp.

MaterialApp(
  home: Navigator( // 'sub-root' navigator. Second in the hierarchy.
    onGenerateRoute: (_) => MaterialPageRoute(
      builder: (_) => FirstScreen(),
      settings: RouteSettings(isInitialRoute: true),
    ),
  ),
);