[whatwg] Proposal for a tab visibility API

[Markus Ernst]

Am 09.12.2010 00:12 schrieb Boris Zbarsky:
> On 12/8/10 5:29 PM, Markus Ernst wrote:
>> Thus, I'd consider an api for detecting the visibility state of every
>> HTML element useful (totally visible, partially visible, hidden - or a
>> percentage value).
>
> This is pretty hard to implement, in general. For example, if I put
> another window over the browser window then whether the content in the
> browser is visible depends on the exact app running in that window, and
> on the parts of it overlapping the browser content, right?

Sure. Some applications might even be partially transparent, like some 
fancy-skinned media players.