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Re: [css-writing-modes][CSS21] propagation of 'direction' from <body> (was Re: [CSSWG] Minutes Telecon 2014-07-09)

From: Simon Pieters <simonp@opera.com>
Date: Mon, 01 Dec 2014 13:47:04 +0100
To: www-style@w3.org, "L. David Baron" <dbaron@dbaron.org>
Message-ID: <op.xp6wgqxridj3kv@simons-mbp>
On Mon, 22 Sep 2014 22:39:32 +0200, L. David Baron <dbaron@dbaron.org>  
wrote:

> On Thursday 2014-07-10 11:28 -0400, Dael Jackson wrote:
>> CSS Background Issue
>> --------------------
> [...]
>>   SimonSapin: Do we only get writing mode direction from the root
>>               element?
>>   Rossen_: I think for IE we always propagate from body or HTML.
>>   Rossen_: We treat it the same way to the root element which HTML
>>            spec says that we take those and leave body so it has a
>>            chance to redefine for overflow or writing. If HTML
>>            doesn't have it we take it from body.
>>   SimonSapin: The spec says don't do that.
>>   Rossen_: Which?
>>   <SimonSapin> http://dev.w3.org/csswg/css-writing-modes/#direction
>>   SimonSapin: Link above
>>   <SimonSapin> "Note that the direction property of the HTML BODY
>>                element is not propagated to the viewport. That
>>                special behavior only applies to the background and
>>                overflow properties."
>>   Rossen_: That spec was written 5 years after we did that
>>            implementation. Maybe it now says something different,
>>            but that's what we do.
>>   Rossen_: It's interesting that it deviates from how we handle
>>            overflow. I would expect the same.
>>   fantasai: We had a legacy constraint that we were hoping wasn't
>>             there for direction.
>>   fantasai: We wanted authors to tag the root.
>>   Rossen_: If you haven't implemented writing-mode, maybe. If you've
>>            had it for a long time then you have an issue and if you
>>            write ignoring that, you can avoid the issue.
>>   fantasai: This is direction. It's been around since the 90's.
>>   fantasai: Everyone's implemented it.
>>   Rossen_: Right.
>>   <plh> (fyi: the note was including in the FPWD of writing modes
>>         back in 2010, but it's not part of CSS2.1)
>
> For what it's worth, the WG explicitly resolved *not* to propagate
> direction from <body> when resolving CSS 2.1 issues; see the
> resolution to Issue 239 in
> http://lists.w3.org/Archives/Public/www-style/2011Mar/0258.html .
>
> I'd be ok with switching to match the background and overflow
> propagation rules if there are sites out there that depend on it,
> but if we do, we should make it an errata to CSS 2.1.

It seems to me that the current situation is that implementors are  
converging towards interoperably propagating direction and writing-mode  
 from body.

https://codereview.chromium.org/758073003

AFAIK, nobody has done research on the Web compat impact of following the  
spec. Is anyone interested in doing the research and implementing the  
spec? If not, I think we should change the spec to match what is  
implemented.

-- 
Simon Pieters
Opera Software
Received on Monday, 1 December 2014 12:46:24 UTC

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