import 'package:flutter/material.dart';

void main() {
  runApp(
    MaterialApp(
      home: MyWidget(),
    ),
  );
}

class MyWidget extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: Center(
          child: RaisedButton(
        child: const Text('Button'),
        color: Colors.orange,
        textColor: Colors.white,
        onPressed: () {
          _showBottomSheetMenu(context);
        },
      )),
    );
  }

   void _showBottomSheetMenu(BuildContext context) {
    showModalBottomSheet(
        context: context,
        shape: RoundedRectangleBorder(
          borderRadius: BorderRadius.vertical(top: Radius.circular(25.0)),
        ),
        builder: (builder) {
          return Container(
            height: 350.0,
            color: Colors.transparent,
            child: Container(
                child: Center(
              child: Text("This is a modal sheet"),
            )),
          );
        });
  }
 
}