Basic Flutter app with a button that shows Toast without using MaterialApp

main.dart

import 'package:flutter/material.dart';
import 'package:fluttertoast/fluttertoast.dart';

void main() {
  runApp(WidgetsApp(
    builder: (context, int) {
      return Container(
          color: Colors.white,
          child:Center(
        child: RaisedButton(
          onPressed: () {
            Fluttertoast.showToast(
                msg: "This is Center Short Toast",
                toastLength: Toast.LENGTH_SHORT,
                gravity: ToastGravity.BOTTOM,
                timeInSecForIos: 1,
                backgroundColor: Colors.red,
                textColor: Colors.white,
                fontSize: 16.0
            );

            },
          child: Text(
            'Hello, world 2!',
            textDirection: TextDirection.ltr,
          ),
        ),
      ));
    },
    color: Colors.blue,
  ));
}