W3C home > Mailing lists > Public > w3c-wai-ua@w3.org > January to March 2001

Re: [Action] Issue 443: Repair of device-dependent author-specifiedbehavior.

From: Ian Jacobs <ij@w3.org>
Date: Wed, 21 Feb 2001 21:06:17 -0500
Message-ID: <3A947419.8169B128@w3.org>
To: Charles McCathieNevile <charles@w3.org>
CC: Jon Gunderson <jongund@uiuc.edu>, w3c-wai-ua@w3.org
Charles McCathieNevile wrote:
> 
> No.
> 
> It is not about guaranteeing access, it is about providing a way to alleviate
> a problem, which (at P1 level) is otherwise guaranteed to prevent access.

My comment about our priority definitions not referring to the 
responsibilities of authors is an important one. The user agent
cannot remove all access barriers alone; the author must contribute.
The definition of P1 is:

  "This checkpoint must be satisfied by user agents, otherwise one 
  or more groups of users with disabilities will find it impossible
  to access the Web. Satisfying this checkpoint is a basic 
  requirement for enabling some people to access the Web."

Substituting:

 "The user agent must emulate all mouse behavior through the
  keyboard, otherwise one or more groups of users with disabilities
  will find it impossible to access the Web."

I don't agree with the substitution since the "otherwise" doesn't
work for me; even if the UA emulates/repairs, one or more 
groups of users will still find it impossible to access the 
Web (as described below). The author's contribution is crucial 
here, and that's not captured in our priority statement.

 - Ian


> I like thje way the proposal is worded, since it makes it clearer just what
> must be done in each situtation, but I disagree that it is a priority 3
> requirement.
> 
> Charles McCN
> 
> On Wed, 21 Feb 2001, Jon Gunderson wrote:
> 
>   Ian,
>   I like the reasoning behind the proposal.  I agree that the repair we have
>   talked about has dubious guarantees of making content accessible.  What do
>   other people think of the proposal?
> 
>   Jon
> 
>   At 01:40 PM 2/21/2001 -0500, Ian Jacobs wrote:
>   >Hello,
>   >
>   >Per my action item assigned at the 15 February 2001
>   >teleconference [1] about issue 443 [2], please consider this
>   >proposal for which device-dependent repair requirements should
>   >appear in UAAG 1.0.
>   >
>   >Checkpoint 1.1 of the 26 January 2001 Guidelines [3] states:
>   >
>   >    "Ensure that the user can operate the user agent fully through
>   >    keyboard input alone, pointing device input alone, and voice
>   >    input alone. [Priority 1]"
>   >
>   >I propose splitting this checkpoint in three (rough wording
>   >here):
>   >
>   >   Checkpoint A: "Ensure that the user can operate the user agent's
>   >   native functionalities through keyboard input alone, pointing
>   >   device input alone, and voice input alone. [Priority 1]"
>   >
>   >   Checkpoint B: "Ensure that the user can operate
>   >   device-independent functionalities specified in content through
>   >   keyboard input alone, pointing device input alone, and voice
>   >   input alone. [Priority 1]"
>   >
>   >   Checkpoint C: "Allow configuration so that the user can operate
>   >   device-dependent functionalities specified in content through
>   >   other devices (e.g., simulate pointing device specific behavior
>   >   through the keyboard). In this configuration, alert the user when
>   >   an active element has device-specific behaviors associated.
>   >   [Priority 3]"
>   >
>   >I think that checkpoint C should be Priority 3 because it is
>   >likely to provide incomplete repair. Thus, it clearly does not
>   >qualify for P1 by definition:
>   >
>   >    "This checkpoint must be satisfied by user agents, otherwise
>   >    one or more groups of users with disabilities will find it
>   >    impossible to access the Web."
>   >
>   >There is no guarantee that if satisfied, checkpoint C will make
>   >access possible. [I would also note that our priority statements
>   >don't say anything about the responsibilities of other
>   >parties. This is clearly an authoring issue first.]
>   >
>   >Consider these scenarios:
>   >
>   >1) The author has created content that is device independent. In
>   >this case, checkpoint B applies.
>   >
>   >2) The author has created content that is device-dependent, but
>   >has also provided alternative content (per WCAG 1.0 checkpoints
>   >9.2 and 11.4). In this case, emulation is not required since the
>   >author has ensured access.
>   >
>   >3) The author has created content that is device-dependent, and
>   >has not provided an alternative. The device-dependent content is
>   >either:
>   >
>   >   a) Content that doesn't really depend on a particular device
>   >      but has just been encoded that way, or
>   >
>   >   b) Content that really does depend on a particular device
>   >      (e.g., a user interface where the user scratches the
>   >      "silver paint" on an electronic lottery ticket to
>   >       reveal a hidden number).
>   >
>   >The user agent can't recognize the difference in general, since
>   >handlers are built with scripts. So that means that, in general,
>   >the user agent is not likely to repair any better content of type
>   >(3a) over content of type (3b).
>   >
>   >Repair in case (3a) is probably useful to some users, can be
>   >carried out automatically, and is technically feasible (e.g., the
>   >UA could throw an "onmouseover" event whenever an "onfocus" event
>   >occurs, or implement a "zap-mouse-to-focus" functionality).
>   >
>   >However, in case (3b), emulation is not likely to help some
>   >users.  Even a tool such as MouseKeys will not help some users
>   >(e.g., users who are blind) interact with the user interface. If
>   >the author has designed content that expressly takes advantage of
>   >the nature of two-dimensional visual space, there's not much
>   >users who are blind can do with certainty. Worse, emulating mouse
>   >events might cause unexpected behavior to occur, thus
>   >disorienting the user.  And, emulation of certain pointing device
>   >events is less obvious (e.g., how do you translate "onmousemove"
>   >to the keyboard?), so repair by the UA would likely be incomplete
>   >on this axis as well.
>   >
>   >In our current definition of "active element", we don't expect
>   >the user agent to recognize (and thus repair) the class of
>   >author-specified behaviors that are encoded through "event
>   >bubbling" techniques.
>   >
>   >Finally, the user agent should not be required to emulate
>   >mouse-specific behaviors that are not controlled by the user
>   >agent (e.g., the case of server-side image maps).
>   >
>   >----------
>   >CONCLUSION
>   >----------
>   >
>   >- Emulation of author-supplied device-specific behaviors seems to
>   >be useful for some cases, and not helpful (or even disorienting)
>   >in others.
>   >
>   >- The user agent is not expected to recognize the useful cases
>   >from the non-useful cases since behaviors are encoded through
>   >scripts today. This means that the user agent couldn't "warn" the
>   >user, for example.
>   >
>   >- Repair functionalities are likely to be incomplete and not
>   >guarantee access, so I think that they should be Priority 3.
>   >
>   >  - Ian
>   >
>   >----------
>   >References
>   >----------
>   >
>   >[1] http://lists.w3.org/Archives/Public/w3c-wai-ua/2001JanMar/0227.html
>   >[2] http://server.rehab.uiuc.edu/ua-issues/issues-linear-lc2.html#443
>   >[3] http://www.w3.org/WAI/UA/WD-UAAG10-20010126/

-- 
Ian Jacobs (jacobs@w3.org)   http://www.w3.org/People/Jacobs
Tel:                         +1 831 457-2842
Cell:                        +1 917 450-8783
Received on Wednesday, 21 February 2001 21:06:22 GMT

This archive was generated by hypermail 2.2.0+W3C-0.50 : Tuesday, 27 October 2009 06:50:38 GMT