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Re: DOM Accessibility Issues: bubbling

From: Al Gilman <asgilman@iamdigex.net>
Date: Wed, 22 Sep 1999 22:56:26 -0400
Message-Id: <199909230308.XAA07412@smtp1.mail.iamworld.net>
To: Jon Gunderson <jongund@staff.uiuc.edu>, w3c-wai-pf@w3.org
Cc: w3c-wai-ua@w3.org
This comment is concerning the third issue dealing with bubbling.

This is not a consensus of PF, DOM or any working group, just some ideas.

At 03:53 PM 9/21/99 -0700, Jon Gunderson wrote: 
>
> Three issues related to User Agent Accessibility Guidelines and the DOM 2
> specification:
>
> 1. Exporting DOM to external applications: Can an external program in a
> standard way have read and write access to the DOM of a user agent.
>
> Review Guideline 6 in trhe current guidelines:
>
> <http://www.w3.org/WAI/UA/WAI-USERAGENT-19990827/>http://www.w3.org/WAI/UA
> /WAI-USERAGENT-19990827/
>
> 2. Timing of access by an external program to the DOM: It is critical
than an
> external assistive technology have high speed access to the DOM of a user
> agent
>
> Review Guideline 6 in trhe current guidelines:
>
> <http://www.w3.org/WAI/UA/WAI-USERAGENT-19990827/>http://www.w3.org/WAI/UA
> /WAI-USERAGENT-19990827/
>
>
> 3. Event Bubbling: With event bubbling it is impossible for a user agent to
> determine which child elements of a element with an event will or will not
> respond to the parent event.  Elements with associated events are considered
> active elements in the user agent guidelines.


What would happen if only the element bearing the event-handler attribute were
treated as active?  Treating all descendants of a script-bearing element as
active elements defeats the purpose of navigating just the active elements
already, it would seem to me.

The fundamental requirement, so far as I know, is to be able to reach all
interactive actions available in the document.  This is satisfied by treating
the element that actually declares the event handler a member of the effective
active-elements set.

To me, the script which checks for what descendant the mouse was in when it is
fired is a violation of the WCAG guideline to use structural markup properly. 
I am afraid that viewing all descendants of a script-bearing element as active
is an over-reaction to a potential abuse.

Is the method (with heredity of 'active' status over subelements of an active
element which handles an event that can bubble) in use in any browser or
assistive technology or combination at present?  Is there any confirmation
with
user testing that it works?

Al


>
> References in user agent guidelines:
>
> Checkpoint 1.2 Ensure that the user can interact with all active elements
of a
> document in a device independent manner. [Priority 1] 
>
> Checkpoint 3.4 Provide time-independent access to time-dependent active
> elements or allow the user to control the timing of changes. [Priority 1] 
>
> Checkpoints 8.4 Allow the user to navigate just among all active elements in
> the document. [Priority 2] 
>
> Checkpoint 9.7 Provide a mechanism for highlighting and identifying
(through a
> standard interface where available) active elements of a document. [Priority
> 3] 
>
> Jon Gunderson, Ph.D., ATP
> Coordinator of Assistive Communication and Information Technology
> Chair, W3C WAI User Agent Working Group
> Division of Rehabilitation - Education Services
> University of Illinois at Urbana/Champaign
> 1207 S. Oak Street
> Champaign, IL 61820
>
> Voice: 217-244-5870
> Fax: 217-333-0248
> E-mail: jongund@uiuc.edu
> WWW: <http://www.staff.uiuc.edu/~jongund>http://www.staff.uiuc.edu/~jongund
> <http://www.w3.org/wai/ua>http://www.w3.org/wai/ua
>
<http://www.als.uiuc.edu/InfoTechAccess>http://www.als.uiuc.edu/InfoTechAccess
Received on Wednesday, 22 September 1999 22:56:26 UTC

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