CustomScrollView's Scrollbar is not draggable when using a center key for a empty sliverlist with an anchor of 1.0 #178863
Description
Steps to reproduce
- Create a CustomScrollView.
- Give it a center key.
- Assign it a anchor of 1.0.
- Pass in a normal sliverlist with some children such that the viewport of the application will become scrollable.
- Pass in a sliverlist with no children present and have that sliverlist hold the center key.
Expected results
When clicking and dragging the scollbar I should be able to navigate up/down the list.
Actual results
When clicking and dragging the scollbar via the mouse you are not able to navigate up/down the list (you can however scroll it - as shown in the provided video).
Code sample
Code sample
import 'package:flutter/material.dart';
/// Flutter code sample for [CustomScrollView].
void main() => runApp(const CustomScrollViewExampleApp());
class CustomScrollViewExampleApp extends StatelessWidget {
const CustomScrollViewExampleApp({super.key});
@override
Widget build(BuildContext context) {
return const MaterialApp(home: CustomScrollViewExample());
}
}
class CustomScrollViewExample extends StatefulWidget {
const CustomScrollViewExample({super.key});
@override
State<CustomScrollViewExample> createState() => _CustomScrollViewExampleState();
}
class _CustomScrollViewExampleState extends State<CustomScrollViewExample> {
@override
Widget build(BuildContext context) {
final items = List<int>.generate(100, (index) => index);
const Key centerKey = ValueKey<String>('bottom-sliver-list');
return Scaffold(
appBar: AppBar(
title: const Text('Bug demo'),
),
body: CustomScrollView(
center: centerKey,
anchor: 1.0,
slivers: <Widget>[
SliverList.builder(
itemCount: items.length,
itemBuilder: (BuildContext context, int index) {
return Container(
alignment: Alignment.center,
color: Colors.blue[200 + items[index] % 4 * 100],
height: 100 + items[index] % 4 * 20.0,
child: Text('Item: ${items[index]}'),
);
},
),
SliverList.builder(
key: centerKey,
itemCount: 0,
itemBuilder: (BuildContext context, int index) {
return Text("This is not going to be present");
},
),
],
),
);
}
}Screenshots or Video
Screenshots / Video demonstration
Screen.Recording.2025-11-20.at.13.23.08.mov
Logs
No response
Flutter Doctor output
Doctor output
[✓] Flutter (Channel stable, 3.35.4, on macOS 15.6 24G84 darwin-arm64, locale en-GB) [96ms]
• Flutter version 3.35.4 on channel stable at /opt/homebrew/share/flutter
• Upstream repository https://github.com/flutter/flutter.git
• Framework revision d693b4b9db (9 weeks ago), 2025-09-16 14:27:41 +0000
• Engine revision c298091351
• Dart version 3.9.2
• DevTools version 2.48.0
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[✗] Android toolchain - develop for Android devices [58ms]
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• Build 16F6
• CocoaPods version 1.16.2
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[!] Android Studio (not installed) [4ms]
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[✓] Connected device (3 available) [5.5s]
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! Doctor found issues in 2 categories.