W3C home > Mailing lists > Public > www-style@w3.org > June 2011

Re: [css3-conditional] feature queries

From: Boris Zbarsky <bzbarsky@MIT.EDU>
Date: Wed, 15 Jun 2011 00:49:22 -0400
Message-ID: <4DF839D2.8060607@mit.edu>
To: Alan Gresley <alan@css-class.com>
CC: www-style@w3.org
On 6/15/11 12:36 AM, Alan Gresley wrote:
> Can you give examples of current and possible future properties and/or
> values

There are currently proposed new values for background-image (e.g. 
gradients, image(), etc), position/display, every single property that 
takes lengths (calc()).  That's off the top of my head after about 5 
second of thought.

> but keeping in mind that support for @supports is currently not
> present and such support may come after certain properties and values
> are un-prefixed and interoperable?

Why does that matter, unless you think CSS development is likely to stop 
entirely in the near future?

> I agree with this point but why should browsers continue to lie?

Because when asked whether 'display' is supported it's a lot easier to 
say 'yes' than to say 'no' if you support all but one value of the property.

More to the point, if you (an implementor) support _all_ the values for 
'display' at some point and return 'yes' as a result and then a new 
value is added in some CSS module that you don't support yet, you won't 
start returning 'no' for 'display' support, right?

So any system that tests for support for support on a per-property basis 
completely falls down when new values are added to properties.... which 
is happening all the time.

 > From my authoring perspective, my main issue has been support of 
background-size
> (either the background-property or in background shorthand).

Those are actually separate questions, no?  A UA can easily support 
background-size on its own but not in the background shorthand... which 
you can't detect without being able to ask whether the 'background' 
property accepts syntax including a size.  Note that obviously all UAs 
will claim to support the 'background' property if you just ask them 
whether they support it.  So even to answer your second question you 
need property/value pair support tests.

-Boris
Received on Wednesday, 15 June 2011 04:50:03 GMT

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