W3C home > Mailing lists > Public > w3c-wai-gl@w3.org > January to March 2007

SC 3.2.5 and warnings

From: Christophe Strobbe <christophe.strobbe@esat.kuleuven.be>
Date: Thu, 08 Feb 2007 15:09:54 +0100
Message-Id: <6.2.5.6.2.20070208150054.02e42770@esat.kuleuven.be>
To: w3c-wai-gl@w3.org

Hi,

In the BenToWeb project, we recently had a discussion about SC 3.2.5.
Success criterion 3.2.5 requires: "Changes of 
context are initiated only by user request." This 
raised a discussion about what kind of user 
actions can be considered as – implicit or 
explicit – requests for changes of context. More 
specifically, it was not sufficiently clear 
whether text cues that warn the user about 
changes of context can make the difference 
between passing or failing the success criterion. 
Success criterion 3.2.2 contains an exception for 
instructions or warning to the user, but success 
criterion 3.2.5 and the intent section of How to 
Meet Success Criterion 3.2.5 [1] do not mention 
warnings. One needs to go to the Benefits section 
and the examples of failure 22 [2] to find any mention of warnings.

The first benefit of SC 3.2.5 contains the 
following example: "individuals who are blind or 
have low vision may have difficulty knowing when 
a visual context change has occurred, such as a 
new window popping up. In this case, warning 
users of context changes in advance minimizes 
confusion when the user discovers that the back 
button no longer behaves as expected."

Example 2 of failure 22 - "Failure of SC 3.2.5 
due to opening windows that are not requested by 
the user" - says: "A user clicks on a link, and a 
new window appears. The original link has no 
associated text saying that it will open a new window."

This means that the value of warnings for changes 
of context is not evident to casual readers. For 
the purpose of the BenToWeb test suite [3] we adopted the following rules:

1. A change of user agent without a warning fails.

2. A change of user agent with a warning passes. 
Example: a link to an MP3 where the link text 
contains the warning "(launches external player)".

3. A change of viewport (i.e. a new browser 
window) without a warning and without 
"target='_blank'" on the link element fails.

4. A change of viewport with "target='_new'" on 
the link element (no warning needed) passes.

5. A change of viewport – i.e. a new window 
launched by means of JavaScript – with a warning passes.

6. A change of focus initiated by activating a 
link or an image map area passes.

7. A change of focus initiated by activating a 
submit button, a reset button or an image button passes.

8. A change of content initiated by activating a 
link or an image map area passes.

9. A change of content initiated by activating a 
submit button or an image button passes.

10. A change of content initiated by activating a 
reset button passes if the result is the original empty form.

The consequence of all this is that HTML pages 
can only link to other documents that browsers 
handle natively, but not to sound, video, 
multimedia, PDF, office documents, unless the 
user is warned about the change of user agent.

[1] 
http://www.w3.org/TR/2006/WD-UNDERSTANDING-WCAG20-20060427/Overview.html#consistent-behavior-no-extreme-changes-context
[2] http://www.w3.org/TR/2006/WD-WCAG20-TECHS-20060427/Overview.html#F22
[3] http://www.bentoweb.org/XHTML1_TestSuite2

Best regards,

Christophe


-- 
Christophe Strobbe
K.U.Leuven - Departement of Electrical 
Engineering - Research Group on Document Architectures
Kasteelpark Arenberg 10 - 3001 Leuven-Heverlee - BELGIUM
tel: +32 16 32 85 51
http://www.docarch.be/ 


Disclaimer: http://www.kuleuven.be/cwis/email_disclaimer.htm
Received on Thursday, 8 February 2007 14:10:05 GMT

This archive was generated by hypermail 2.2.0+W3C-0.50 : Monday, 7 December 2009 10:47:49 GMT