Proposal: Update style of WebView2 scrollbars

[Poopooracoocoo]

Proposal: Update style of WebView2 scrollbars

Summary

Add support for automatically hiding scrollbars.
Add support for the setting to turn that off.
Update the style of WebView2 scrollbars

Rationale

• consistency

Scope

Capability	Priority
This proposal will allow developers to accomplish W	Must
This proposal will allow end users to accomplish X	Should
This proposal will allow developers to accomplish Y	Could
This proposal will allow end users to accomplish Z	Won't

Important Notes

Open Questions

[StephenLPeters]

@codendone @chigy @predavid FYI

[krschau]

At least for scroll bar style, this is something that can be done by setting an environment variable from inside your application:

Environment.SetEnvironmentVariable("WEBVIEW2_ADDITIONAL_BROWSER_ARGUMENTS", "--enable-features=OverlayScrollbar,OverlayScrollbarWinStyle,OverlayScrollbarWinStyleAnimation");