Overflow widget can be visible with 'Overflow.visible' but untouchable.

gistfile1.txt

import 'package:flutter/material.dart';

final Color darkBlue = Color.fromARGB(255, 18, 32, 47);

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

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      theme: ThemeData.dark().copyWith(scaffoldBackgroundColor: darkBlue),
      debugShowCheckedModeBanner: false,
      home: Scaffold(
        body: Center(
          child: MyWidget(),
        ),
      ),
    );
  }
}

class MyWidget extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return Center(child: AnimationTest());
  }
}

class AnimationTest extends StatefulWidget {
  _AnimationTestState createState() => _AnimationTestState();
}

class _AnimationTestState extends State<AnimationTest> {
  bool toggle = false;
  @override
  Widget build(BuildContext context) {
    return Container(
        width: 200,
        height: 200,
        color: Colors.grey,
        child: Stack(
          overflow: Overflow.visible,
          children: [
          AnimatedPositioned(
              duration: Duration(milliseconds: 300),
              left: toggle ? -100 : 0,
              bottom: 50.0,
              child: RaisedButton(
                  child: Text("hello"),
                  onPressed: () => setState(() {
                        toggle = !toggle;
                        print(toggle);
                      })))
        ]));
  }
}