Security/Reviews/ExitFullScreenFocusChange

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Item Reviewed

Don't exit fullscreen when focusing window on different display
Target	Full Query ID Summary Priority Status 724554 Don't exit fullscreen when focusing window on different display -- RESOLVED 805613 Handle multiple fullscreen documents concurrently -- RESOLVED 2 Total; 0 Open (0%); 2 Resolved (100%); 0 Verified (0%);

{{#set:SecReview name=Don't exit fullscreen when focusing window on different display

|SecReview target=

Full Query

ID	Summary	Priority	Status
724554	Don't exit fullscreen when focusing window on different display	--	RESOLVED
805613	Handle multiple fullscreen documents concurrently	--	RESOLVED

2 Total; 0 Open (0%); 2 Resolved (100%); 0 Verified (0%);

}}

Introduce the Feature

Goal of Feature, what is trying to be achieved (problem solved, use cases, etc)

• Multiple monitors lose fullscreen on focus change
  • video full screen in one monitor and work on something else on the other
  • or have 2 monitors have different things full screen
  • Current plan is to show the full-screen warning again for 4 seconds whenever a full-screen page regains focus.

Mac Spaces questions

• Will this allow you to use multiple spaces on a single monitor? (With one in full-screen mode and another showing another app, or another Firefox tab)
  • Probably? might need to ask zpao.
• With multiple monitors, mac's concept of spaces and full-screen tends to affect all monitors at once

What solutions/approaches were considered other than the proposed solution?

• Showing the warning again for 4 seconds upon return seems like overkill.
  • How about just one second?
  • How about a smaller warning? (Perhaps a watermark, if we can make it hard to hide)

Why was this solution chosen?

• `

Any security threats already considered in the design and why?

`

Threat Brainstorming

• The "warning when switching between two full-screen windows" might be defeatable, when a single site is full-screen in both windows (immersive demos and games)
  • What if a web page lies about where focus is?
    • It can't prevent mouse clicks
      • Lies about where the mouse cursor is?
  • This isn't really worse than the situation with one full-screen window

{{#set: SecReview feature goal=* Multiple monitors lose fullscreen on focus change

• • video full screen in one monitor and work on something else on the other
  • or have 2 monitors have different things full screen
  • Current plan is to show the full-screen warning again for 4 seconds whenever a full-screen page regains focus.

Mac Spaces questions

• Will this allow you to use multiple spaces on a single monitor? (With one in full-screen mode and another showing another app, or another Firefox tab)
  • Probably? might need to ask zpao.
• With multiple monitors, mac's concept of spaces and full-screen tends to affect all monitors at once

|SecReview alt solutions=* Showing the warning again for 4 seconds upon return seems like overkill.

• • How about just one second?
  • How about a smaller warning? (Perhaps a watermark, if we can make it hard to hide)

|SecReview solution chosen=*` |SecReview threats considered=' |SecReview threat brainstorming=* The "warning when switching between two full-screen windows" might be defeatable, when a single site is full-screen in both windows (immersive demos and games)

• • What if a web page lies about where focus is?
    • It can't prevent mouse clicks
      • Lies about where the mouse cursor is?
  • This isn't really worse than the situation with one full-screen window

}}

Action Items

Action Item Status	None
Release Target	`
Action Items
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|Feature version=` |SecReview action items=` }}