[pointerevents] Support hovering button states

jacobrossi has just created a new issue for 
https://github.com/w3c/pointerevents:

== Support hovering button states ==
[Originating 
thread](http://lists.w3.org/Archives/Public/public-pointer-events/2015AprJun/0080.html)

The latest proposal looks something like this:

* Allow ````buttons```` to change while hovering
* Restrict pointerdown/up to only be for left buttton, touch, and 
stylus tip on screen (e.g. button value of 0)

We should also consider:
* should ````click```` fire for hovering button presses?
* should there be a new event, e.g. ````pointerbuttonschange```` that 
fires in this case?

Note that the latter point could also be useful for chorded button 
scenarios where you want an easy way to know another button changed 
even if the pointer is down.

See https://github.com/w3c/pointerevents/issues/14

Received on Wednesday, 17 June 2015 17:52:56 UTC