Please insert an explicit requirement for user agents to convert aria-activedescendant into MSAA for focus and location

Many authors are creating structures like toolbars where the whole toolbar
has a tabIndex=0 and the ARIA spec recommends aria-activedescendant and
keyboard handling to move among toolbar items.  This is cited as an
acceptable way rather than applying to tabIndex=0 to the currently focused
item.  The way I read the current requirements is that the user agent would
only need to provide focus indication and coordinates for the entire toolbar
and not the actual active-descendant because it doesn’t have a level of
keyboard access that the user agent can detect except for the presence of
the aria-activedescendant attribute.

Several user agents do appear to support this correctly such as IE and
Firefox, however, it would appear safest if this need would explicitly be
called out.  This affects users with low vision who use screen magnification
software.  This software would rely on location information for proper
tracking.

An example of the technique with radio button is provided below:

http://oaa-accessibility.org/example/29/



Best Regards,



Jonathan