W3C home > Mailing lists > Public > www-style@w3.org > December 2015

Re: [css-will-change] establishing containing block for fixed-positioned elements

From: Tab Atkins Jr. <jackalmage@gmail.com>
Date: Fri, 4 Dec 2015 14:31:20 -0800
Message-ID: <CAAWBYDB45rLkUA=V1+guN7hH1AKAFjs5JUZQdVtX39vAakxAWQ@mail.gmail.com>
To: "L. David Baron" <dbaron@dbaron.org>
Cc: www-style list <www-style@w3.org>
On Tue, Nov 24, 2015 at 4:28 PM, L. David Baron <dbaron@dbaron.org> wrote:
> https://drafts.csswg.org/css-will-change/#valdef-will-change-custom-ident
> says:
>
>   If any non-initial value of a property would cause the element to
>   generate a containing block for fixed-position elements,
>   specifying that property in will-change must cause the element to
>   generate a containing block for fixed-position elements.
>
> I think this should instead say:
>
>   If any non-initial value of a property would cause the element to
>   generate a containing block for fixed-position elements,
>   specifying that property in will-change must cause the element to
>   generate a containing block for fixed-position _and
>   absolute-position_ elements.
>
> I don't think we need special will-change handling for the
> properties that establish a containing block for absolute-position
> but not fixed-position elements (i.e., the position property), but
> the properties that establish a containing block for
> fixed-positioned elements *also* do so for absolutely-positioned
> elements.  And it would be bizarre (and defeat the point of the
> special will-change handling) to establish only half of the
> containing-block nature and not all of it.
>
> (Also see
> https://lists.w3.org/Archives/Public/public-fx/2015OctDec/0035.html
> about making this clearer in css-transforms and css-filters.)
>
>
> While here, it's probably also worth using "absolutely positioned"
> and "fixed positioned" as
> https://drafts.csswg.org/css-containment/#containment-paint does,
> rather than "fixed-position" and "absolute-position".

Fixed.

~TJ
Received on Friday, 4 December 2015 22:32:09 UTC

This archive was generated by hypermail 2.4.0 : Friday, 25 March 2022 10:08:58 UTC