[presentation-api] Make select algo reject in ancestor and descendant browsing contexts

tidoust has just created a new issue for 
https://github.com/w3c/presentation-api:

== Make select algo reject in ancestor and descendant browsing 
contexts ==
The [select a presentation 
display](https://w3c.github.io/presentation-api/#selecting-a-presentation-display)
 algorithm rejects the Promise "if there is already an unsettled 
Promise from a previous call to start on any PresentationRequest in 
the same controlling browsing context".

This is done to allow only one user prompt to select a presentation 
display at a time for a given tab. However, since `start` can be 
called by nested browsing contexts as well, I think "the same 
controlling browsing context" does not capture the notion of "tab" 
that we need.

There does not seem to be a term to say "all the browsing contexts 
that compose the tab" in HTML:
http://www.w3.org/TR/html51/browsers.html#nested-browsing-contexts

We could perhaps say "Let top be the [top-level browsing 
context](http://www.w3.org/TR/html51/browsers.html#top-level-browsing-context)
 of the current browsing context. If there is already an unsettled 
Promise from a previous call to start on any PresentationRequest in 
top or in the [list of the descendant browsing 
contexts](http://www.w3.org/TR/html51/browsers.html#list-of-the-descendant-browsing-contexts)
 of top..."

Issue initially raised in: 
https://github.com/w3c/presentation-api/pull/392#discussion_r92910190

Please view or discuss this issue at 
https://github.com/w3c/presentation-api/issues/394 using your GitHub 
account

Received on Monday, 19 December 2016 14:08:25 UTC