Flutter Web: Cannot scroll with mouse down (drag) (Flutter 2.5+)

My final solution was a combination of the suggestions, wanting drag scrolling everywhere, so used this:

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      scrollBehavior: MaterialScrollBehavior().copyWith(
        dragDevices: {PointerDeviceKind.mouse, PointerDeviceKind.touch, PointerDeviceKind.stylus, PointerDeviceKind.unknown},
      ),
      ...

Simple enough…