RSM Prototype #3 PageView Test

- Test PageView update state.

lib/main_pageview_test.dart

@@ -0,0 +1,94 @@
+import 'package:flutter/gestures.dart';
+import 'package:flutter/material.dart';
+
+void main() {
+  runApp(MyApp());
+}
+
+class MyApp extends StatefulWidget {
+  @override
+  State<MyApp> createState() => MyAppState();
+}
+
+class MyAppState extends State<MyApp> {
+  int parentCounter = 10;
+
+  @override
+  Widget build(BuildContext context) {
+    return MaterialApp(
+      title: 'Flutter Demo',
+      theme: ThemeData(
+        primarySwatch: Colors.blue,
+      ),
+      scrollBehavior: MaterialScrollBehavior().copyWith(
+        dragDevices: {
+          PointerDeviceKind.mouse,
+          PointerDeviceKind.touch,
+          PointerDeviceKind.stylus,
+          PointerDeviceKind.unknown
+        },
+      ),
+      home: Scaffold(
+        body: PageView(
+          physics: AlwaysScrollableScrollPhysics(),
+          controller: PageController(viewportFraction: 0.8),
+          children: [
+            CounterPage(),
+            CounterPage(),
+            CounterPage(), // Add as many pages as you want
+          ],
+        ),
+      ),
+    );
+  }
+}
+
+class CounterPage extends StatefulWidget {
+  @override
+  _CounterPageState createState() => _CounterPageState();
+}
+
+class _CounterPageState extends State<CounterPage> {
+  int _counter = 0;
+
+  void _incrementCounter() {
+    setState(() {
+      _counter++;
+    });
+  }
+
+  @override
+  Widget build(BuildContext context) {
+    return Scaffold(
+      appBar: AppBar(
+        title: Text('Counter Page'),
+      ),
+      body: Center(
+        child: Column(
+          mainAxisAlignment: MainAxisAlignment.center,
+          children: <Widget>[
+            Text(
+                'Parent Counter: ${context.findAncestorStateOfType<MyAppState>()?.parentCounter}'),
+            ElevatedButton(
+                onPressed: () {
+                  context
+                      .findAncestorStateOfType<MyAppState>()
+                      ?.parentCounter += 1;
+                  context
+                      .findAncestorStateOfType<MyAppState>()
+                      ?.setState(() {});
+                },
+                child: Text('Increment Parent Counter')),
+            Text('You have pushed the button this many times:'),
+            Text('$_counter', style: Theme.of(context).textTheme.headline4),
+          ],
+        ),
+      ),
+      floatingActionButton: FloatingActionButton(
+        onPressed: _incrementCounter,
+        tooltip: 'Increment',
+        child: Icon(Icons.add),
+      ),
+    );
+  }
+}