Feature Request: Detect and indicate when the entire screen is being shared

[lyntonjay]

Firefox is my main browser and I'd love to see this supported.

When using getDisplayMedia() for screen sharing, it would be helpful if Firefox exposed a reliable way for web apps to detect whether the user is sharing their entire screen versus just a window or tab.

Currently, the MediaTrackSettings returned from getDisplayMedia() includes a displaySurface property (e.g., "monitor", "window", "browser"), but support and consistency in Firefox is limited. Chrome already supports this reliably, so there's a working reference implementation to compare against.

Improving this in Firefox would let web apps:

• Warn users if they're sharing their whole screen (privacy risk — accidental exposure of other windows, notifications, etc.)
• Prompt users to switch to sharing a specific window/tab instead
• Adjust UI behavior based on sharing scope

Suggested improvement: Ensure track.getSettings().displaySurface reliably returns "monitor" when the full screen is shared, across all supported OSes (Windows, macOS, Linux), and document this behavior clearly for web developers.

[Jon]

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[asher-fx]

Hi @lyntonjay, thanks very much for the note on screen sharing. We are currently working on implementing tab share and making the entire screen sharing UX more cohesive. Will keep you updated.