Accessibility and CSS [was: Changing Yelp to use GtkHtml1 instead of GtkHtml2]

[Bill Haneman <bill haneman sun com>]

John said:
...

> So we've got a relatively straightforward technical question here:
> 
> Does Yelp need CSS to properly display help files? 
> 
> Sander's views are the only ones I care about, since he's the one trying
> to make the whole stylesheet thing work, so I guess the answer is "no,
> we don't need CSS".
> 
> Do I have this right? Is there something we're missing, like a possible
> need for CSS to provide a11y for the help?

Actually I've received pretty clear information from the w3c's web
accessibility guidelines folks that, in the future, CSS and DOM support
will be required for compliance with their User Agent Guidelines,
barring significant changes in the UAG.  It's not clear that Yelp will
need to conform, but it's an issue for HTML/XML renderers generally.

There are three main accessibility "musts" for a help browser:

(1) It must respect system themes, in this case GTK+ RC-file themes when
using the default engine.  That means that all test attribution like
sizes must be relative to/with respect to the GTK+ default font.  Sander
has been looking at doing this with stylesheets and I have agreed to
prepare patches for gtkhtml2 to make its base text rendering sizes use
the GTK+ RC-file font.

(2) It must support keyboard navigation, provide visible indication of
focus on screen, and be fully usable in mouseless mode.

(3) It must support ATK interfaces, in particular AtkText and AtkImage,
and AtkTable (if frames are used).

I believe that gtkhtml2 has significant support for (2) and (3) at this
time and Sander and I are working on (1).  It's not clear that we can
meet all of these requirements with gtkhtml1 in the 2.0 timeframe, so
from an accessibility perspective I would argue strenuously against a
change unless the gtkhtml1 team can commit to meeting these needs ASAP.

-Bill

> Cheers,
> 
> John