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Re: [CSS21] table cells establishing pseudo-stacking contexts (was Re: [CSSWG] Minutes Telecon 2013-04-05)

From: L. David Baron <dbaron@dbaron.org>
Date: Wed, 1 May 2013 16:28:04 -0700
To: fantasai <fantasai.lists@inkedblade.net>
Cc: www-style@w3.org
Message-ID: <20130501232804.GA19984@crum.dbaron.org>
On Wednesday 2013-05-01 15:32 -0700, fantasai wrote:
> On 04/06/2013 11:16 AM, L. David Baron wrote:
> >
> >However, if cells are pseudo-stacking contexts, then the background
> >of a later cell can draw on top of the content of an earlier cell.
> >This requires, in turn, defining exactly *which* of these table part
> >backgrounds are part of the pseudo-stacking context established by
> >the table cell.
> >
> >Combining these two makes me think that, in turn, if cells are to be
> >pseudo-stacking contexts, then either:
> >  (a) the backgrounds of all of the table parts except for the table
> >      (i.e., column groups, columns, row groups, rows, and cells)
> >      should be part of background layer in the pseudo-stacking
> >      context established by the cell, or
> >  (b) none of the backgrounds (not even the cell's) should be part of
> >      the pseudo-stacking context established by the cell.
> >
> >I don't have a strong preference between these options.  However, I
> >would be opposed to other options, such as including the table's
> >background in the cell's pseudo-stacking context, or including the
> >cell background but none of the other table part backgrounds,
> >because I don't think these options fit with the existing model, and
> >thus I think they would lead to extra implementation complexity and
> >extra difficulty for authors who want to understand what's
> >happening.
> 
> There's also the interesting interaction with collapsed table borders.
> In the case of the collapsed model, you really want the borders to
> belong to the table and not the cell; and if they belong to the table,
> then so must the cell background, or else it draws over the cell's own
> borders. Hence for collapsed tables, Model B makes the most sense--
> the cell only owns its own content, and its borders and background both
> belong to the table.
> 
> For separate borders model, however, I think Model A makes the most
> sense, because you want the ability to transform a table cell with
> its border and background.
> 
> So I think from an authoring perspective, it makes the most sense to
> do model A for separate-border tables, and model B for collapsed-border
> tables.

I think it's way too complex to have two models here.  We should
pick one.  What's wrong with using (b) for both?

-David

-- 
𝄞   L. David Baron                         http://dbaron.org/   𝄂
𝄢   Mozilla                           http://www.mozilla.org/   𝄂
Received on Wednesday, 1 May 2013 23:28:29 UTC

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