RE: CSS 2: priorities in cascading order

Hakon Lie [mailto:howcome@w3.org] wrote (second-level quotes are my own):
> > Actually, the infrastructure is there to support this in IE4 - we expose
a
> > rich stylesheet object model.  All it would require is a wrapper
> > application to our Web browser control that provided UI for these hooks.
> > (In essence, I'm saying we implement the code necessary to do this, but
> > not the UI.)
>Good, would Microsoft be able to publish a wrapper application?

Heh.  Call MY bluff, will ya.  :^)  I just built a rough proof-of-concept;
it has a very stripped-down UI, but it does work; and better yet, I utilized
the context-menu extension of IE4 instead of building a wrapper application,
so it will work in your usual IE4.  I'll probably refine this a bit later;
for now, the files, instructions and a test set are attached in a WinZip
file.

> > >Adding "!accessibility" will provide a hook which
> > >corresponds e.g. to the "Accessibility" dialog box of MS IE 4.
> > 
> > Not completely true - the semantics are ever-so-slightly-different (then
the
> > user would be required to say "use this color always", not "ignore
colors
> > set in the documents"). 
>
>I see the difference between the two statements, but I still believe
>you can use CSS to express all semantics.

No; you can use CSS to express the BEHAVIOUR, but not the semantic.  CSS
doesn't allow you to say "ignore this class of rules/properties," it can
only say "use this rule instead of the other one."  You can get the same
behaviour, but only if you assume wildcards and a new, more important
"!important", as well as assuming all the browser defaults come from the
user stylesheet (which they don't, in IE).

>When the user declares that
>colors in the incoming document is to be ignored, the UA increases the
>weight of the color declarations in the browser and user style sheets
>from normal to "accessibility", and voila!

Yes, this will obtain the same visual behaviour.  As Al Gilman indirectly
pointed out, though, this approach essentially only works if you specify
"everything on everything" - you can't, for example, "avoid small italics"
without specifying font-size and/or font-style on all possible elements.

I'm not trying to say CSS can never provide a complete accessibility
solution; I'm just saying that in my opinion, to address the accessibility
issues properly, there would need to be a lot more hooks and features
provided in CSS.  Providing a couple of minor hooks like "!required" and
then claiming the cascade fixes all will not encompass a complete solution
(again, in my opinion) - that's like saying those with temporary or
permanent disabilities can remove all stylesheets and presentation tags &
attributes, and they'll just get the text.  It's a true statement, but it's
short-changing those communities.  If my only disability is the inability to
read italics below 8pt, I shouldn't have to predefine font sizes for all
elements (or predefine font-style: none).

-Chris Wilson
 Internet Explorer Team
 cwilso@microsoft.com
 


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Received on Monday, 22 December 1997 13:23:47 UTC