concerns with SC 3.2.1

I have some concerns with Level 1 Success Criterion 3.2.1 [1]  with regard 
to the DHTML Accessibility roadmap.  I have implemented a tab panel where 
the user can arrow from tab panel to tab panel.  When the new panel tab 
receives focus, the contents of that panel are updated.  This duplicates 
the navigation behavior of a tab panel in Windows.  I am concerned that 
this may violate SC 3.2.1, since the tab panel can be the container for 
the content of the page and thus a change of context is occurring.   I 
brought this up at the Seattle Face to Face and I think this is allowed 
since the user is initiating the change of focus and context via the arrow 
key and not via the standard mechanism of tabbing from item to item. Based 
on the "How to Meet" document for this SC, the intent is to prevent an 
unexpected form submission, unexpected focus change,  or complete and 
unexpected reload of the page.  I don't believe the tab panel falls into 
any of these categories but want to be certain. 

The current Web paradigm is to implement the tab panel navigation as a 
link.  In this case the user would use the tab key to set focus to a tab 
and then press enter to load the panel contents.   The DHTML Accessibility 
roadmap allows me to implement the UI in a more standard operating system 
manner and  make the Web UI match the operating system UI.  I want to make 
certain that this paradigm shift in Web behavior is allowed at Level 1 in 
WCAG.

Attached is an example file that will work in Firefox 1.5 and IE 6 with 
the keyboard.  With Firefox 1.5 and WindowEyes 5.5 the tab panel 
information will be spoken if you rename the file with an xhtml extension 
(it needs to be served as application/xhtml+xml for full DHTML 
accessibility). For example, when the first tab of 5 receives focus the 
following is spoken, "tab name, 1 of 5, tab control".


[1] When any component receives focus, it does not cause a change of 
context. 
http://www.w3.org/TR/WCAG20/guidelines.html#consistent-behavior-receive-focus


Becky Gibson
Web Accessibility Architect
                                                       
IBM Emerging Internet Technologies
5 Technology Park Drive
Westford, MA 01886
Voice: 978 399-6101; t/l 333-6101
Email: gibsonb@us.ibm.com