- From: Steve Faulkner <faulkner.steve@gmail.com>
- Date: Thu, 20 Apr 2017 06:41:02 +0100
- To: Charles McCathie Nevile <chaals@yandex-team.ru>
- Cc: John Foliot <john.foliot@deque.com>, public-webapps <public-webapps@w3.org>, "www-style@w3.org" <www-style@w3.org>, W3C WAI Accessible Platform Architectures <public-apa@w3.org>, CB Averitt <cb.averitt@deque.com>
- Message-ID: <CA+ri+V=MTrkyYF1+HpjA9do81XH7E0FjTsVrHEewu41H-vezfA@mail.gmail.com>
Note: i wrote about this issue a while back: Short note on improving usability of scrollable regions <https://www.paciellogroup.com/blog/2016/02/short-note-on-improving-usability-of-scrollable-regions/> and filed bugs on edge <https://connect.microsoft.com/IE/feedbackdetail/view/2324891/css-overflow-auto-does-not-allow-scroll-via-keyboard> and chrome <https://code.google.com/p/chromium/issues/detail?id=584618> <https://www.paciellogroup.com/blog/2016/02/short-note-on-improving-usability-of-scrollable-regions/> -- Regards SteveF Current Standards Work @W3C <http://www.paciellogroup.com/blog/2015/03/current-standards-work-at-w3c/> On 19 April 2017 at 23:55, <chaals@yandex-team.ru> wrote: > Hi John, > > I think this problem is, unfortunately, squarely an issue for the HTML > specification, and also means filing bugs on browsers if they aren't > already there. > > Note that it isn't new: https://github.com/w3c/html/issues/292 describes > the problem, and shows that people have known about it for quite a while. > > It certainly seems to me that Firefox has the right behaviour, and > everyone else doesn't. > > For that reason, I will start a new thread about this on public-html - the > public email list for the HTML specification. > > I also encourage the APA group to look carefully at the issue mentioned > above. > > 19.04.2017, 23:16, "John Foliot" <john.foliot@deque.com>: > > Greetings CSS and Web Platform Working Groups, > > Recently, one of our Subject Matter Experts at Deque created a test page > that unearthed a... question. After a careful review of the specs (and a > quick double-check with our buddy Glazou), and he recommended to bring this > to you for some input, as there may be a gap here or unintended behavior > - an undefined collision in Daniel's words. > > First, the test page can be found at http://a11yideas.com/ > testcode/scrollareas.html > > There are two scrollable <div> elements with no focusable elements > contained within. The first <div> has a tabindex="0", the second <div> > does not. > > Both <div>s have the following CSS declaration: > > > .scroll { > background-color: #ddd; > height: 140px; > width: 200px; > overflow: auto; > padding: 6px; > margin: 10px; > } > > > The current spec <https://www.w3.org/TR/CSS2/visufx.html#propdef-overflow> > for 'overflow' states: > > > > The behavior of the 'auto' value is user agent-dependent, but should cause > a scrolling mechanism to be provided for overflowing boxes. > > > > Our testing shows that, indeed, in every mainstream browser we've tested, > because the content is longer than the declared height of the <div> that > the browsers are adding the scroll bars. > > HOWEVER, with the exception of Firefox, if a content author does not > explicitly also set the tabindex="0" to the <div> (even though the browser > has added scroll bars) that keyboard-only users cannot tab "into" the > scrollable <div>, nor can they scroll that <div>'s content via the keyboard > only. > > As you can imagine, this is a significant accessibility concern. Yet, when > I read the spec, it doesn't seem to address this scenario, at least not > specifically. > > At the heart of the question is: if a browser adds a function that > requires user-input/interaction, should the browser also be responsible for > adding that 'modified' element to the tab order when appropriate (like in > this example)? > > Logic would suggest to me that the current Firefox behavior is the correct > behavior, since the user-agent (browser) is adding the scroll bars 'when > required' (per "auto"), and when the browser adds those scroll bars, that > the scroll bars should also be automatically added to the tab-order. But > the spec is silent on that, and to date the only browser that appears to be > doing this is FF. > > Alan and Rossen, I know that the CSS WG is in Tokyo for a F2F this week, > and perhaps you might have time to discuss this there? > > At this point, I am unsure where I should file a bug (if, indeed, a bug is > the right response), but today we have inconsistent behavior in the > browsers, and exclusive of Firefox, I believe there is an unintended but > serious accessibility miss in the current CSS Spec. Perhaps what the spec > should say is something like: > > > > The behavior of the 'auto' value is user agent-dependent, but should cause > a tab-focusable scrolling mechanism to be provided for overflowing boxes. > > > However, I'll leave that to either CSS WG or Web Plat WG to work out: > ideally I'd like to just know what the *intent* was of either WG (and I'm > guessing that CSS WG is the better group to answer the question). > > Currently, in the absence of a definitive declaration, here at Deque we > will be failing any scrollable <div> without tabindex="0", as without that > declaration the scrollable <div> is unusable to keyboard-only users, but > we'd love to have a specific spec to point to (and point our clients to as > well). > > Thanks! > > JF > -- > John Foliot > Principal Accessibility Strategist > Deque Systems Inc. > john.foliot@deque.com > > Advancing the mission of digital accessibility and inclusion > > > > -- > Charles McCathie Nevile - standards - Yandex > chaals@yandex-team.ru - - - Find more at http://yandex.com > >
Received on Thursday, 20 April 2017 05:42:20 UTC