[Page Visibility] Spec -- privacy concern

One major privacy concern I (and others I chatted with on Mozilla's 
#developers IRC) have is that third-party scripts (like ad providers, etc) 
would be able to monitor this type of data (page visibility) and gain 
valuable (to them!) information which a user might not want them to have, 
such as how long I stay viewing a page, etc.

I think this is possibly an intractable concern, unless there's some way to 
enforce that only scripts which originated from the same exact domain as the 
page could access such data, not all JS from any location.

Alternatively (and possibly more usefully, for the user education/knowledge 
perspective), maybe this feature could be an opt-in prompt similar to 
geolocation... so that user-agents have to ask the user for permission (and 
allow it to be a rememberable preference) before giving that information to 
the page (of course, only if the page tries to access it).

The prompt could be something like: "The site you are viewing wants to 
monitor some aspects of how you use the browser window to view this page, 
possibly for optimizing the performance while the page is inactive in your 



Received on Friday, 13 May 2011 23:50:50 UTC