Repository: flutter
Issue: UI bug: Pointer hover events pass through DraggableScrollableSheet
Labels: framework,f: scrolling,a: desktop,a: mouse,has reproducible steps,P2,found in release: 3.7,found in release: 3.11,team-framework,triaged-framework

DraggableScrollableSheet does not prevent pointer hover events from passing through.

## Steps to Reproduce

**main.dart** 
A UI that stacks a DraggableScrollableSheet on top of the page content.
*also includes an example of a workaround*
```dart
import 'package:flutter/material.dart';

void main() {
  runApp(MyApp());
}

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(title: 'Flutter dss-hover-pass-through bug', home: MyHomePage());
  }
}

class MyHomePage extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return Stack(
      children: <Widget>[
        Scaffold(
          appBar: AppBar(
            title: Text('DraggableScrollableSheet hover-pass-through bug'),
            actions: <Widget>[
              IconButton(
                  icon: Icon(Icons.info), tooltip: "Action tooltip", onPressed: () {}),
            ],
          ),
          body: Center(
            child: Column(
              mainAxisAlignment: MainAxisAlignment.center,
              children: <Widget>[
                Padding(
                  padding: const EdgeInsets.all(16.0),
                  child: Text(
                    'The button below and the appbar action above should not receive hover events when covered by the DraggableScrollableSheet.'
                        ' To demonstrate, drag the red sheet over the buttons and mouse over them. The tooltips will display when they should not.'
                        ' The blue sheet implements a workaround by wrapping its content with a MouseRegion widget.',
                  ),
                ),
                Tooltip(
                  message: 'Button tooltip',
                  child: RaisedButton(child: Text('Button'), onPressed: () {}),
                ),
              ],
            ),
          ),
        ),
        // A sheet through which the hover events will pass-through.
        DraggableScrollableSheet(
          initialChildSize: .2,
          maxChildSize: 1,
          minChildSize: .2,
          builder: (BuildContext _, ScrollController sc) {
            return Card(
              color: Colors.red[100],
              child: SingleChildScrollView(
                controller: sc,
                child: Center(child: Text("DraggableScrollableSheet")),
              ),
            );
          },
        ),
        // A sheet with a workaround for the bug.
        DraggableScrollableSheet(
          initialChildSize: .1,
          maxChildSize: 1,
          minChildSize: .1,
          builder: (BuildContext _, ScrollController sc) {
            return MouseRegion(
              child: Card(
                color: Colors.lightBlue[100],
                child: SingleChildScrollView(
                  controller: sc,
                  child: Center(child: Text("DraggableScrollableSheet with workaround")),
                ),
              ),
            );
          },
        ),
      ],
    );
  }
}
```

**Expected results:** <!-- what did you want to see? -->
The content hidden by the DraggableScrollableSheet to not react to mouse hover events.

**Actual results:** <!-- what did you see? -->
Tooltips triggered by mouse hover events are shown for content hidden by the DraggableScrollableSheet.