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Re: CSS2.1: computed value of z-index

From: L. David Baron <dbaron@dbaron.org>
Date: Wed, 2 Jan 2008 17:49:32 -0500
To: www-style@w3.org
Message-ID: <20080102224932.GA18088@ridley.dbaron.org>

On Wednesday 2008-01-02 12:54 -0800, Maciej Stachowiak wrote:
> http://www.w3.org/TR/CSS21/visuren.html#z-index
>
> z-index only applies to positioned elements, however, its computed value is 
> "as specified". Since the computed value can be exposed to script via 
> getComputedStyle(), I suggest that it would be more useful if the computed 
> value is "as specified for positioned elements, otherwise auto" so that 
> scripts get the value actually used.

Changing the "Computed value" line would also affect z-index:
inherit, which makes it a little messy.  It would add one more edge
to the graph of computed value dependencies between properties
(which we need to keep acyclic).

Of course, getComputedStyle() depends on the CSS2.0 concept of
computed value, which is different (it's a stage after the CSS2.1
computed value, matching the CSS2.1 used value for many properties).
Another possibility is changing getComputedStyle() without changing
inheritance, which might be reasonable here.  (But we'd need a spec
to put that in; I'm not sure if we have one yet.)

-David

-- 
L. David Baron                                 http://dbaron.org/
Mozilla Corporation                       http://www.mozilla.com/
Received on Wednesday, 2 January 2008 22:49:40 GMT

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