import 'package:flutter/material.dart';

const Color darkBlue = Color.fromARGB(255, 18, 32, 47);

void main() {
  runApp(MyApp());
}

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      theme: ThemeData.dark().copyWith(
        scaffoldBackgroundColor: darkBlue,
      ),
      debugShowCheckedModeBanner: false,
      home: Scaffold(
        body: Center(
          child: MyWidget(),
        ),
      ),
    );
  }
}

class MyWidget extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return Scaffold(
        body: Center(
          child: MenuAnchor(
            menuChildren: [
              ParentMenuModal(),
            ],
            builder: (context, controller, widget) {
              return ElevatedButton(
                child: const Text("Click me"),
                onPressed: () {
                  controller.open();
                },
              );
            },
          ),
        )
    );
  }
}

class ParentMenuModal extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return DropdownMenu(
      label: const Text('Menu'),
      initialSelection: "1",
      dropdownMenuEntries: ["1", "2", "3"]
          .map(
            (it) =>
            DropdownMenuEntry(
              value: it,
              label: it,
            ),
      )
          .toList(),
    );
  }
}