import 'package:flutter/material.dart';

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

class MyApp extends StatelessWidget {
  const MyApp({super.key});

  @override
  Widget build(BuildContext context) {
    return const MaterialApp(
      debugShowCheckedModeBanner: false,
      home: Example(),
    );
  }
}

class Example extends StatelessWidget {
  const Example({super.key});

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      theme: ThemeData(
        popupMenuTheme: const PopupMenuThemeData(
          shape: RoundedRectangleBorder(
            borderRadius: BorderRadius.all(
              Radius.circular(40),
            ),
          ),
        ),
      ),
      home: Scaffold(
        body: Center(
          child: PopupMenuButton<void>(
            clipBehavior: Clip.hardEdge,
            itemBuilder: (BuildContext context) {
              return <PopupMenuEntry<void>>[
                const PopupMenuItem<void>(child: Text('Some action')),
              ];
            },
          ),
        ),
      ),
    );
  }
}