bug fix #4

example/lib/features_choices/choices_main.dart

@@ -8,10 +8,14 @@ import '../features_header.dart';
 import '../keep_alive.dart';
 
 class FeaturesChoices extends StatelessWidget {
+  final scrollController = ScrollController();
+
   @override
   Widget build(BuildContext context) {
     return Scrollbar(
+      controller: scrollController,
       child: ListView(
+        controller: scrollController,
         addAutomaticKeepAlives: true,
         children: <Widget>[
           KeepAliveWidget(

example/lib/features_modal/modal_main.dart

@@ -12,10 +12,14 @@ import '../features_header.dart';
 import '../keep_alive.dart';
 
 class FeaturesModal extends StatelessWidget {
+  final scrollController = ScrollController();
+
   @override
   Widget build(BuildContext context) {
     return Scrollbar(
+      controller: scrollController,
       child: ListView(
+        controller: scrollController,
         addAutomaticKeepAlives: true,
         children: <Widget>[
           KeepAliveWidget(

example/lib/features_multi/multi_main.dart

@@ -9,10 +9,14 @@ import '../features_header.dart';
 import '../keep_alive.dart';
 
 class FeaturesMulti extends StatelessWidget {
+  final scrollController = ScrollController();
+
   @override
   Widget build(BuildContext context) {
     return Scrollbar(
+      controller: scrollController,
       child: ListView(
+        controller: scrollController,
         addAutomaticKeepAlives: true,
         children: <Widget>[
           KeepAliveWidget(

example/lib/features_option/option_main.dart

@@ -10,10 +10,14 @@ import '../features_header.dart';
 import '../keep_alive.dart';
 
 class FeaturesOption extends StatelessWidget {
+  final scrollController = ScrollController();
+
   @override
   Widget build(BuildContext context) {
     return Scrollbar(
+      controller: scrollController,
       child: ListView(
+        controller: scrollController,
         addAutomaticKeepAlives: true,
         children: <Widget>[
           KeepAliveWidget(

example/lib/features_single/single_main.dart

@@ -9,10 +9,14 @@ import '../features_header.dart';
 import '../keep_alive.dart';
 
 class FeaturesSingle extends StatelessWidget {
+  final scrollController = ScrollController();
+
   @override
   Widget build(BuildContext context) {
     return Scrollbar(
+      controller: scrollController,
       child: ListView(
+        controller: scrollController,
         addAutomaticKeepAlives: true,
         children: <Widget>[
           KeepAliveWidget(

example/lib/features_tile/tile_main.dart

@@ -11,10 +11,14 @@ import '../features_header.dart';
 import '../keep_alive.dart';
 
 class FeaturesTile extends StatelessWidget {
+  final scrollController = ScrollController();
+
   @override
   Widget build(BuildContext context) {
     return Scrollbar(
+      controller: scrollController,
       child: ListView(
+        controller: scrollController,
         addAutomaticKeepAlives: true,
         children: <Widget>[
           StickyHeader(