W3C home > Mailing lists > Public > www-style@w3.org > September 2014

Re: Scroll focus when reaching the end of a scrollable element

From: Tab Atkins Jr. <jackalmage@gmail.com>
Date: Tue, 23 Sep 2014 08:27:39 -0700
Message-ID: <CAAWBYDCSRUvJJeNqiREGFU6p6ugi0Kcc1MT50R9VqTx4nSK9Dg@mail.gmail.com>
To: Rick Byers <rbyers@chromium.org>
Cc: Eric Andrew Lewis <eric.andrew.lewis@gmail.com>, "www-style@w3.org" <www-style@w3.org>
[Rick, please don't top-post http://wiki.csswg.org/tools/www-style ]

On Tue, Sep 23, 2014 at 7:21 AM, Rick Byers <rbyers@chromium.org> wrote:
> On Sat, Sep 20, 2014 at 9:05 PM, Eric Andrew Lewis
> <eric.andrew.lewis@gmail.com> wrote:
>>
>> Hi friends,
>>
>> I'd like to chat about scroll focus when reaching the end of a scrollable
>> element.
>>
>> In most modern browsers, when you scroll to the end of a scrollable
>> element (i.e. overflow-y: scroll applied), scroll focus bubbles up to the
>> next scrollable element. Here's a quick codepen example of that, and a video
>> example.
>>
>> This makes moving through the content of a scrollable element a touchy
>> user experience: if you try to quickly scroll through it, you run the risk
>> of losing your place in the page.
>>
>> I would love control over this in CSS, so that I can explicitly declare
>> that a container should own scroll focus when it is being interacted with by
>> mouseover or touch swiping.
>>
>> There are a number of Javascript libraries that let you create scrollable
>> elements which have built-in support with this alternate behavior - see
>> Control.scrollBar and jQuery Custom Scrollbar. These libraries also
>> implement custom scrollbars, but that's not a part of this discussion.
>
> I agree this is a behavior web developers should be able to customize.
> Another scenario it comes up in is when you have UI that is logically a
> pop-up window (perhaps position:fixed).  Scrolling inside of it shouldn't
> attempt to scroll any elements in it's containing block chain (I've seen
> many websites in Chrome where the geyed-out page in the background scrolls
> in such a case).
>
> IE has -ms-scroll-chaining for precisely this problem.  Does that do
> everything you'd want?
>
> On the blink team we're mainly interested in lower level primitives (such as
> the beforescore event we just proposed here) that enable a much richer set
> of customization.  I'd personally still support standardizing something like
> scroll-chaining if we also had the low-level primitives that "explain" it.

Yes, I think scroll-chaining does exactly what's requested, and I'm
happy enough with its name and syntax that I'd be fine adopting it
directly.

~TJ
Received on Tuesday, 23 September 2014 15:28:32 UTC

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