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RE: [css3-background] border-radius color transitions using gradients recommended but undefined

From: Sylvain Galineau <sylvaing@microsoft.com>
Date: Tue, 26 Jan 2010 07:33:59 +0000
To: fantasai <fantasai.lists@inkedblade.net>
CC: "www-style@w3.org" <www-style@w3.org>, Brian Manthos <brianman@microsoft.com>
Message-ID: <045A765940533D4CA4933A4A7E32597E102FB4D4@TK5EX14MBXC113.redmond.corp.microsoft.com>

> From: fantasai [mailto:fantasai.lists@inkedblade.net]
 
> I'm not comfortable with normatively requiring a particular gradient
> form or a particular type of corner join in css3-background. I don't
> think we have clear answers as to what would look best--other than it
> should be a type of conic gradient--so I want to leave implementations
> free to experiment. It's fine IMO to leave this detail of border
> rendering undefined in CSS3: it gives it a chance to evolve as
> implementers learn from each other and from author feedback.

I understand the intent. But I am not comfortable with recommending that a CR property 
have an undefined behavior that is important to designers just as it is seeing broad 
adoption. It's one thing for browsers to experiment with background gradients behind 
-moz, -webkit, -ms or -o. The author can and must choose to depend on such features.

But if it's a side-effect of border-radius in the next Firefox or IE, the author has 
no choice in the matter. One browser may use a gradient, and the other may not. Or they
may do it differently.  So while both finally agree on the shape of the border based
on the same syntax, a new interop issue has been introduced when 2+ border colors are
specified. 

If we don't know what this should look like and would like to experiment further, we can
keep css3-background at the WD stage. Or we can remove this recommendation; this will allow
border-radius to interoperate in a testable manner and browsers can still experiment with 
gradient transitions behind the prefixed version of this property until CSS4, if they so desire.

If authors *do* want us to recommend incompatibility in this area so that browser vendors can
gather their feedback, it's a different matter. I am not getting that message, however. 

So again, I would love to hear from other implementors.
Received on Tuesday, 26 January 2010 07:34:37 GMT

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