On desktop platforms, provide support for interactive scrollbars.

This is needed to rewrite the devtools inspector in Flutter as the scrollbars are important to make the large amount of content shown more navigable.
https://docs.flutter.dev/tools/devtools/inspector

For my use case, making the scrollbars match a specific platform's scrollbar look and feel is not critical.