Focus traversal testing

main.dart

import 'package:flutter/material.dart';

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

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      theme: ThemeData.dark(),
      home: MyHomePage(),
    );
  }
}

class MyHomePage extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: Center(
        child: SizedBox(
          width: double.infinity,
          child: Row(
            mainAxisAlignment: MainAxisAlignment.spaceEvenly,
            children: [
              for (var i = 0; i < 2; i++)
                FocusableActionDetector(
                  onFocusChange: (focused) {
                    if (!focused) {
                      print('Have left focus group');
                    }
                  },
                  child: Column(
                    mainAxisAlignment: MainAxisAlignment.center,
                    children: [
                      for (var i = 0; i < 3; i++)
                        SizedBox(
                          width: 150,
                          child: TextField(),
                        ),
                    ],
                  ),
                ),
            ],
          ),
        ),
      ),
    );
  }
}