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Re: Positioned Layout proposal

From: Tab Atkins Jr. <jackalmage@gmail.com>
Date: Mon, 18 Oct 2010 17:17:34 -0700
Message-ID: <AANLkTi=xtFPysCoHYX1vFDLJ6eKzTFP=yZw-iozT060w@mail.gmail.com>
To: robert@ocallahan.org
Cc: www-style list <www-style@w3.org>
On Mon, Oct 18, 2010 at 4:25 PM, Robert O'Callahan <robert@ocallahan.org> wrote:
> Unfortunately, the problem of cyclic dependencies is very serious. It's not
> restricted to cycles of explicit positioning constraints.
>
> For example, the geometry of positioned elements can affect whether
> overflow:auto elements have overflow, which affects whether scrollbars are
> present, which can affect the available width and hence the layout of any of
> the descendants of the overflow:auto element. Furthermore, the presence or
> absence of a horizontal scrollbar can affect the height of an element and
> hence the positions of many other elements inside and outside the
> overflow:auto element. The only way I can think of to resolve those issues
> in a sane way for your spec would be to have your specially positioned
> elements not contribute to the "scrollable overflow area" of any of their
> ancestor elements. That may cause problems for some of your use cases.
>
> Even if we do that, the size of a positioned element still affects the
> layout of its descendants, and therefore with your spec you can have cycles
> where some dependencies are explicit positioning constraints and some are
> implicit layout constraints.
>
> I think you should focus on improving this area of your proposal, since I
> think it's where most of the risk and complexity lies.

Good point.

~TJ
Received on Tuesday, 19 October 2010 00:19:10 GMT

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