AlertDialog with StatelessWidget

main.dart

import 'package:flutter/material.dart';

void main() => runApp(MyApp());

class MyApp extends StatelessWidget {
  showAppDialog(BuildContext context) {
    print("Showing app dialog");
    showDialog(context: context,
              builder: (context) {
              return AlertDialog(
              title: const Text(
                "This is a dialog that works.",
              ),
              icon: const Icon(Icons.delete),
              actions: [
                TextButton(
                    onPressed: () {
                      Navigator.of(context).pop();
                    },
                    child: const Text("OK"),
                ),
              ],
            );

              });
  }
  
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Flutter Demo',
      debugShowCheckedModeBanner: false,
      theme: ThemeData(
        primarySwatch: Colors.blue,
      ),
      home: Scaffold(body: SafeArea(child: Builder(
        builder: (context) {
          return TextButton(child: Text("Show dialog"), onPressed: () => showAppDialog(context),);
        }
      ))),
    );
  }
}