Flutter Subwidget Navigation (Nested Navigation)

Nested navigation https://flutter.dev/docs/cookbook/effects/nested-nav

More tips: https://stackoverflow.com/questions/55213680/in-a-nested-navigator-structure-of-flutter-how-do-you-get-the-a-specific-naviga

Flutter package: https://pub.dev/packages/qlevar_router

Global keys: https://medium.com/flutter-community/navigate-without-context-in-flutter-with-a-navigation-service-e6d76e880c1c

Layout widgets https://flutter.dev/docs/development/ui/widgets/layout