Support for visual indicator of shared surface

[ayroblu]

When sharing a surface in Slack, I noticed that there is a large green border around the shared surface. I believe this happens on other apps too like Zoom. There's a clear advantage to this that it highlights the shared content, and you don't "forget" that you're sharing part of your screen.
For backwards compatibility, it could be an option in getDisplayMedia video constraint.

[eladalon1983]

In Chrome, sharing a tab draws a blue rectangle around the shared tab. We have been considering doing something similar for shared windows and screens. It's not immediately clear to me that it makes sense for this to be an extra option/hint/constraint/setting in getDisplayMedia(). Usually such browser-level UX is left to the discretion of the browser itself. Do you have an argument for why it should be a getDisplayMedia() hint?

[ayroblu]

No strong opinion, just "backwards compatibility"

Edit: theoretically you might want to customise so having on and off is kinda sufficient but probably not worth it as it's not a Dom surface

[eladalon1983]

Typically, the user agent (browser) exercises discretion over its own UX. Especially in privacy-sensitive contexts like this one. Ceding control to the Web application is uncommon and requires a strong rationale.