[webkit-dev] Removing support for the -khtml- (and -apple-?) vendor prefixes

Peter Beverloo peter at lvp-media.com
Mon Jul 12 09:20:13 PDT 2010

On Mon, Jul 12, 2010 at 18:00, Ryosuke Niwa <rniwa at webkit.org> wrote:
> While converting all -khtml- properties to -webkit- may not be appropriate because there could be incompatible implementation of certain property, there are properties starting with -khtml- that are supposed to be supported by WebKit.  See bugs such as https://bugs.webkit.org/show_bug.cgi?id=11825.  Not supporting these will be a burden for some Web developers as they need to add both -khtml- and -webkit- to specify one property.
> Best,
> Ryosuke Niwa
> On Mon, Jul 12, 2010 at 1:53 AM, Peter Beverloo <peter at lvp-media.com> wrote:
>> Good day,
>> While going through WebCore for some CSS research I'm currently doing,
>> I came across a piece of code[1] which translates all "-khtml-" and
>> "-apple-" vendor-prefixes to "-webkit-". This effectively means
>> "-apple-transform" and "-khtml-transform" can both be used instead of
>> "-webkit-transform". I am unaware of the rationales behind the apple
>> vendor-prefix, but I'd like to propose removing support for the
>> KHTML-prefix.
>> My main argument for this is that WebKit and KHTML are, in my opinion,
>> two separate engines by two separate vendors. The port occurred eight
>> years ago, and code in both projects has changed significantly ever
>> since. When Microsoft announced support for "-webkit-text-size-adjust"
>> in IE Mobile it was argued that browsers should not implement
>> properties with prefixes "belonging" to other vendors, which seems to
>> be exactly what WebKit is doing with the KHTML prefix.
>> I understand the history of supporting -khtml-, and have heard from
>> the KHTML project that they implement the -webkit- prefix as well.
>> However, considering that WebKit has grown significantly in the past
>> few years and that all code changes basically made KHTML and WebKit
>> two individual rendering engines, with individual CSS support, I
>> believe it would be appropriate for support to be dropped.
>> Regards,
>> Peter Beverloo
>> http://peter.sh/
>> [1] http://trac.webkit.org/browser/trunk/WebCore/css/CSSParser.cpp#L5583
>> [2] http://blogs.msdn.com/b/iemobile/archive/2010/05/10/javascript-and-css-changes-in-ie-mobile-for-windows-phone-7.aspx
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I decided to take this issue to the mailing lists before posting a
patch for such reasons. The Apple documentation which is referred
to[1] in that bug has been updated to use WebKit's own vendor prefix,
so I suspect the impact of removing -khtml- will be rather small.
After all, that regression happened about four years ago.

I will upload a patch within a few hours.

Peter Beverloo

[1] http://developer.apple.com/mac/library/documentation/AppleApplications/Conceptual/SafariJSProgTopics/Tasks/DragAndDrop.html

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