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Re: [css-will-change] 'will-change' and custom properties

From: Tab Atkins Jr. <jackalmage@gmail.com>
Date: Fri, 4 Dec 2015 14:20:56 -0800
Message-ID: <CAAWBYDCTmoWUOAQNUOcOx5v9KBzT95fe8VbxPZSVPat5fZg7WA@mail.gmail.com>
To: "L. David Baron" <dbaron@dbaron.org>
Cc: www-style list <www-style@w3.org>
On Tue, Nov 24, 2015 at 3:44 PM, L. David Baron <dbaron@dbaron.org> wrote:
> https://drafts.csswg.org/css-will-change/#valdef-will-change-custom-ident
> defines the behavior of 'will-change: <custom-ident>'.  It has a
> number of statements that "If a[ny] non-initial value of a property
> would cause"...
>
> Xidorn pointed out to me in
> https://bugzilla.mozilla.org/show_bug.cgi?id=1227501 that
> technically this applies to custom properties, but it probably isn't
> meant to.  I don't think implementations should be required to trace
> through the uses of a custom property to see if the custom property
> could possibly cause the creation of a stacking context or the
> generation of a containing block for fixed-positioned elements.
> That seems like a lot of work for very little benefit... and
> will-change is intended to make things faster, not slower!
>
> I think this definition should explictly exclude custom properties
> from having these effects.

Agreed, it's not intended that that line apply to such extreme "action
at a distance" effects.

I've specced that custom property names must have no effect, including
the side-effect things.  That work?

~TJ
Received on Friday, 4 December 2015 22:21:45 UTC

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