[webkit-dev] -khtml- and -apple- CSS prefixes

Adam Barth abarth at webkit.org
Fri Mar 8 15:09:05 PST 2013

I've posted a patch to limit the -apple- and -khtml- CSS vendor


My understanding is that I also need to add a runtime flag in order to
fully hide these prefixes from the web because Safari and Dashboard
share the same WebCore binary on Mac OS X.

I found the following entry in Settings.in:

usesDashboardBackwardCompatibilityMode initial=false,

However, some of the paces we need to check this flag do not have easy
access to the Page and therefore have trouble finding the Settings

Would it be possible to use a global static flag to hide these
prefixes from the web?  I don't understand the details of how Safari
and Dashboard share WebCore to know if a global static flag would work


On Fri, Mar 1, 2013 at 4:57 PM, Maciej Stachowiak <mjs at apple.com> wrote:
> I think we'll want to take these out for Apple ports as soon as we can check
> prevalence in older Apple-specific content (e.g. Dashboard widgets).

On Fri, Mar 1, 2013 at 9:11 AM, David Hyatt <hyatt at apple.com> wrote:
> I agree with you that this would be pretty terrible. We definitely don't want developers doing that.

> On Feb 28, 2013, at 6:02 PM, Adam Barth <abarth at webkit.org> wrote:
> I noticed this comment on the Hacker News thread about Paul Irish's
> recent blog post:
> ---8<---
> "CSS parsing is the same, though. Slurping up your CSS and turning it
> into CSSOM’s pretty standard. Yeah, though Chrome accepts just the
> -webkit- prefix whereas Apple and other ports accept legacy prefixes
> like -khtml- and -apple-."
> Using this information, can you target Chrome with the webkit- prefix
> and Safari with the apple- prefix? Specifying the apple- prefix after
> webkit- will ensure that Safari uses that one, right?
> --->8---
> http://news.ycombinator.com/item?id=5302150
> If developers start using this technique, it might be harder to remove
> these prefixes in the future.  Chromium's experience removing these
> prefixes has been quite positive.  We ran into one compatibility
> problem on apple.com, which Apple was gracious enough to fix.
> I'd recommend that the rest of the ports disable
> ENABLE(LEGACY_CSS_VENDOR_PREFIXES) to remove support for the -khtml-
> and -apple- CSS prefixes before it's too late.

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