Re: [Page Visibility] Spec -- privacy concern

On 5/13/11 9:10 PM, Bryan McQuade wrote:
> I agree with Arvind that this is a minor addition to existing
> information that is already available. For instance it is already
> possible to infer whether you are in the background/foreground in
> Chrome by monitoring the frequency with which a timer fires.

For what it's worth, the same is true in the upcoming Firefox 5.

But the important part is that that behavior is NOT required by any 
spec.  If the user installs an extension that tells all pages to act 
like they're visible, that's fine.  If they user changes prefs to make 
it look like they're all invisible, that's up to them.

This is an important thing to keep in mind, imo: the browser must be 
allowed to lie to the visibility APIs if the user asks it to.

-Boris