[whatwg] Proposal for a tab visibility API

[Aryeh Gregor]

On Tue, Jan 4, 2011 at 6:50 PM, Glenn Maynard <glenn at zewt.org> wrote:
>  * “visible” : the full-size page content may be at least partially
> visible on at least one screen.
>  * “hidden” : the full-size page content is not visible to the user at all.

I'd even say

* "hidden": the full-size page content is guaranteed not to be visible
to the user at all.
* "visible": the full-size page content may or may not be visible to the user.

Browsers just can't reasonably account for things like the tab being
on a second monitor that's turned off or who knows what.  You can only
guarantee that it's hidden, not that it's visible.