Entering fullscreen without transient activation

[michaelwasserman]

What problem are you trying to solve?

Web applications might want to enter fullscreen without transient activation, to implement advanced windowing capabilities. For example, a virtual desktop client might automatically extend a fullscreen session onto a newly connected display, or make content fullscreen on two displays at once.

What solutions exist today?

There is no adequate solution today, but some capabilities are pertinent:

• The Window Management API provides relevant multi-screen content placement features (MDN).
• User Agents widely support configurations that block or allow the creation of popup windows without transient activation, with spec support in step #8 of 'The rules for choosing a navigable'

How would you solve it?

Extend step #5 of the Element.requestFullscreen() algorithm to accommodate user agent configurations that permit fullscreen requests without transient activation. See this Explainer for more detail.

Anything else?

This compliments #161