More follow-up from the UA discussion today

I found the conversation excellent, though at the same time somewhat
frustrating in terms of the difficulty of the problem.   These thoughts were
percolating as we wound up the call:

A user agent provides a user interaction framework for Web content.

A user agent may be a host to other user agents, with the expectation that
the hosted UAs also conform to and do not conflict with the hosting UA's or
host platform's (OS) accessibility features.

A user agent may be hosted by other applications that are not UAs; in this
case the UA's accessibility features must conform to and not conflict with
the hosting application and platform (OS) accessibility features.  For
example, a Web browser component contained within a desktop application used
to display help information.

Some rich internet applications, hosted by UAs, blur the line between user
agent and Web content. We might call this a hybrid RIA/UA. The hosted RIA/UA
may provide their own user interface handling but must do so in accordance
with both WCAG and UAAG. The RIA/UA must support accessibility through
integration with the host UA's DOM and/or via direct support for the host
platform's accessibility architecture.

mark