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Re: [CSS21] Description of clearance issue [285] that's incorrectly folded into Issue 203

From: Anton Prowse <prowse@moonhenge.net>
Date: Tue, 22 Mar 2011 20:53:06 +0100
Message-ID: <4D88FE22.6000400@moonhenge.net>
To: "www-style@w3.org" <www-style@w3.org>
CC: fantasai <fantasai.lists@inkedblade.net>, "L. David Baron" <dbaron@dbaron.org>, Arron Eicholz <Arron.Eicholz@microsoft.com>
On 22/03/2011 20:19, fantasai wrote:
> On 03/21/2011 01:32 AM, Anton Prowse wrote:
>> The subsequent URI, Testcases, Resolution and Status should be filed
>> as a new Issue, whose summary should be "Problems with
>> the second clearance calculation" or similar

> http://wiki.csswg.org/spec/css2.1#issue-285

>> The clause "within its parent block" does cause the introduction of
>> the second calculation to fail, since the float only moves
>> upwards if the clearing element's parent block moves upwards, and so
>> the second calculation is /always/ redundant as things
>> currently stand.

>> the argument for ignoring [the second calculation] seems to be that
>> switching to honouring it causes browsers to fail Acid2 and hence
>> would require Acid2 to be changed.
> The argument isn't about Acid2 specifically -- we could just ask Hixie to
> fix Acid2 if that were the only problem. The problem is that, because we
> have interop across all web browsers, there may be a signficant web
> compatibility issue with changing their behavior.

> we do not have enough time to evaluate web compat and make an appropriate
> decision.

OK (although I note that the second calculation was only introduced in 
2007 when it was believed that the spec was pretty much finished, so 
there must have been more willingness to take the risk at that time).

If the second calculation is to be made optional, please can the 
following requests be considered:

(a) David's post [1] be listed as a URL for Issue 285, since it 
succinctly describes what the problem is.

(b) The Resolution to Issue 285 be edited to remove reference to Acid2 
and introduce the reasoning that fantasai gives above.

(c) The resolution be changed from permitting "calculation of 
hypothetical position with respect to the parent block" to permitting 
the second calculation to be omitted.  It would be a significant 
editorial failure to not make it clear that the choice of positioning 
reference is exactly equivalent to the choice of whether to perform the 
second calculation; we're starting to make real progress in clarifying 
this part of the spec, and so it would be a shame to take a step backwards.

Anton Prowse
Received on Tuesday, 22 March 2011 19:53:46 UTC

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