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Re: bidi embedding for block-level elements

From: Ian Hickson <ian@hixie.ch>
Date: Fri, 23 Jul 2010 20:35:36 +0000 (UTC)
To: fantasai <fantasai.lists@inkedblade.net>
Cc: Simon Montagu <smontagu@smontagu.org>, www-html@w3.org, 'WWW International' <www-international@w3.org>, "public-i18n-core@w3.org" <public-i18n-core@w3.org>, "www-style@w3.org" <www-style@w3.org>
Message-ID: <Pine.LNX.4.64.1007232029340.7242@ps20323.dreamhostps.com>
On Wed, 17 Mar 2010, fantasai wrote:
> On 03/17/2010 04:01 PM, Ian Hickson wrote:
> > On Mon, 18 Jan 2010, fantasai wrote:
> > > On 01/14/2010 12:49 AM, Simon Montagu wrote:
> > > > On 01/11/2010 11:35 PM, fantasai wrote:
> > > > > On 11/26/2009 10:54 PM, Simon Montagu wrote:
> > > > > > 
> > > > > > I assume your Gecko example is using a very recent version of 
> > > > > > Gecko, such as a nightly build or a beta of Firefox 3.6? I 
> > > > > > fixed this issue only a few months ago.
> > > > > > 
> > > > > > The HTML standard does specify what to do in this case, see 
> > > > > > http://www.w3.org/TR/REC-html40/struct/dirlang.html#style-bidi:
> > > > > > 
> > > > > > "When a block element that does not have a dir attribute is 
> > > > > > transformed to the style of an inline element by a style 
> > > > > > sheet, the resulting presentation should be equivalent, in 
> > > > > > terms of bidirectional formatting, to the formatting obtained 
> > > > > > by explicitly adding a dir attribute (assigned the inherited 
> > > > > > value) to the transformed element."
> > > > > > 
> > > > > > In practice, however, since browsers are not consistent, 
> > > > > > authors will have to use CSS properties to achieve the 
> > > > > > expected results.
> > > > > 
> > > > > Does this mean applying "unicode-bidi: embed" to all block-level 
> > > > > elements? Because that seems like it fulfill those requirements.
> > > > 
> > > > I was thinking in terms of applying "unicode-bidi: embed" ad hoc 
> > > > whenever applying "display: inline" to a specific element, but 
> > > > applying it wholesale to all block-level elements will also work, 
> > > > of course.
> > > 
> > > In that case, I suggest the we add it to the sample default style 
> > > sheet for HTML 4 in the CSS2.1 appendix, and recommend the HTMLWG 
> > > add some wording about block-level elements defining bidi embedding 
> > > boundaries to the HTML5 spec (and perhaps using CSS's "unicode-bidi: 
> > > embed" rule as an example).
> > 
> > Can you confirm what rule should be added to the HTML5 recommended 
> > style rules? This is an area where this has changed a lot over time 
> > (e.g. CSS2 used to have something like this then it was removed) so 
> > I'd like to make sure I get this exactly right and that everyone 
> > agrees it's the right thing to do.
> 
> <selector representing all HTML5 block-level elements> {
>   display: block;      /* I assume you already have this somewhere */
>   unicode-bidi: embed; /* This is the new rule to add. */
> }
>
> <selector representing all HTML5 list-item elements> {
>   display: list-item;  /* Assumed to exist already */
>   unicode-bidi: embed; /* This is the new rule to add. */
> }
> 
> title, table, tbody, thead, tfoot, tr, td, th {
>   unicode-bidi: embed;
> }

This would mean you couldn't have more than about 60 inline <div>s nested 
inside each other without bidi breaking down. Is that an acceptable risk? 
It seems like it would be a weird thing to tell authors.

-- 
Ian Hickson               U+1047E                )\._.,--....,'``.    fL
http://ln.hixie.ch/       U+263A                /,   _.. \   _\  ;`._ ,.
Things that are impossible just take longer.   `._.-(,_..'--(,_..'`-.;.'
Received on Friday, 23 July 2010 20:36:14 GMT

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