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[csswg-drafts] [cssom-view] New feature - scroll-boundary-behavior (an extension of -ms-scroll-chaining)

From: Majid Valipour via GitHub <sysbot+gh@w3.org>
Date: Mon, 28 Nov 2016 15:05:56 +0000
To: public-css-archive@w3.org
Message-ID: <issues.opened-192028934-1480345555-sysbot+gh@w3.org>
majido has just created a new issue for 
https://github.com/w3c/csswg-drafts:

== [cssom-view] New feature - scroll-boundary-behavior (an extension 
of -ms-scroll-chaining) ==
We are proposing standardization of "-ms-scroll-chaining" with some 
modification. The details of the proposal can be found in this 
[WICG](https://discourse.wicg.io/t/generic-scroll-chaining-prevention-mechanism-or-expand-standardize-ms-scroll-chaining/1811)
 where it is being incubated but here is the executive summary of 
proposed feature:

`scroll-boundary-behavior: propagate | contain | none`

* `propagate`: propagate scroll to the parent scroller. If there is no
 parent scroller (e.g., viewport) user-agent may perform a default 
action (e.g. navigation) or show any appropriate overscroll UI 
affordance. This is the default value.
* `contain`: do not propoagate. The user agent may show an appropriate
 overscroll UI affordance such as glow/bounce etc.
* `none`: same as contain but also prevents any overscroll UI 
affordance e.g. bounce or glow.
There will be scroll-boundary-behavior-{x,y} long-hands too.


Here are the differences compared to existing `-ms-scroll-chaining` 
which is fairly limited in functionality:
1. Applies to all user scrolls (not just touch/touchpad)
2. Per axis control (matching overflow-{x,y})
3. Meaningful and useful definition of chaining behavior at viewport 
level
3. Additional control over bounce/glow affordances
 
I think CSSOM View is probably the right spec to host this new 
attribute as it provides an API to control certain aspects of 
scrolling (similar to `scroll-behavior` in this respect). 

There is some agreement on WICG that the proposed changes are 
reasonable and useful. So if you think this is the right spec to 
standardize I can start working on a pull request with appropriate 
changes to make the proposal more concrete. Any feedback on 
functionality and naming is also very welcome and appreciated.

Please view or discuss this issue at 
https://github.com/w3c/csswg-drafts/issues/769 using your GitHub 
account
Received on Monday, 28 November 2016 15:06:03 UTC

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