Add nested scroll example

@@ -11,6 +11,7 @@ import 'modals/modal_fit.dart';
 import 'modals/modal_inside_modal.dart';
 import 'modals/modal_will_scope.dart';
 import 'modals/modal_with_navigator.dart';
+import 'modals/modal_with_nested_scroll.dart';
 import 'modals/modal_with_scroll.dart';
 
 import 'examples/cupertino_share.dart';
@@ -219,7 +220,7 @@ class _MyHomePageState extends State<MyHomePage> {
                                     scrollController: scrollController),
                           )),
                   ListTile(
-                      title: Text('Cupertino Modal with WillPopScope'),
+                      title: Text('Modal with WillPopScope'),
                       onTap: () => showCupertinoModalBottomSheet(
                             expand: true,
                             context: context,
@@ -228,6 +229,15 @@ class _MyHomePageState extends State<MyHomePage> {
                                 ModalWillScope(
                                     scrollController: scrollController),
                           )),
+                  ListTile(
+                      title: Text('Modal with Nested Scroll'),
+                      onTap: () => showCupertinoModalBottomSheet(
+                            expand: true,
+                            context: context,
+                            builder: (context, scrollController) =>
+                                NestedScrollModal(
+                                    scrollController: scrollController),
+                          )),
                 ],
               ),
             ),

+import 'package:flutter/cupertino.dart';
+import 'package:flutter/material.dart';
+
+class NestedScrollModal extends StatelessWidget {
+  final ScrollController scrollController;
+
+  const NestedScrollModal({Key key, this.scrollController}) : super(key: key);
+
+  @override
+  Widget build(BuildContext context) {
+    return NestedScrollView(
+      
+        physics: ScrollPhysics(parent: PageScrollPhysics()),
+        headerSliverBuilder: (BuildContext context, bool innerBoxIsScrolled) {
+          return <Widget>[
+            SliverList(
+              delegate: SliverChildListDelegate(
+                [
+                  Container(height: 300, color: Colors.blue),
+                ],
+              ),
+            ),
+          ];
+        },
+        body: ListView.builder(
+           controller: scrollController,
+          itemBuilder: (context, index) {
+            return Container(
+              height: 100,
+              color: index.isOdd ? Colors.green : Colors.orange,
+            );
+          },
+          itemCount: 12,
+        ));
+  }
+}