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Re: Feature queries

From: Rijk van Geijtenbeek <rijk@opera.com>
Date: Mon, 14 Dec 2009 00:36:39 +0100
To: "WWW Style" <www-style@w3.org>
Message-ID: <op.u4wg7dx8icz8n2@acer-laptop.lan>
Op Sun, 13 Dec 2009 05:51:22 +0100 schreef Tab Atkins Jr.  
<jackalmage@gmail.com>:

> On Sat, Dec 12, 2009 at 8:45 AM, Steven Simpson <ss@comp.lancs.ac.uk>  
> wrote:
>> On 09/12/09 18:42, Tab Atkins Jr. wrote:
>>> On Wed, Dec 9, 2009 at 1:48 AM, fantasai  
>>> <fantasai.lists@inkedblade.net> wrote:
>>>
>> @supports {
>>>>  tag {
>>>>    background: white;
>>>>    color: gray;
>>>>  }
>>>>
>>>>  tag {
>>>>    color: white;
>>>>    text-shadow: black 0 0 4px !support;
>>>>  }
>>>>
>> }

I suppose you'd normally put the first declaration outside the  
supports-block?

>>> This seems like a much worse idea for backward-compat reasons.  Legacy
>>> clients that don't understand !support will blithely apply the
>>> color:white and just ignore the next line like normal.
>>
>> Any better if the scope is @-marked explicitly (as shown above)?  The
>> whole thing will be skipped if not recognised (right?), and it allows
>> other rules that don't contain !support to be dropped.
>
> Yes, that is better.  Best of both worlds, actually; the only
> sacrifice is that you're having to throw down a bit more syntax.  You
> get things ignored in legacy UAs that don't understand the @supports
> rule, and you minimize the chances of authors using this to
> browser-detect rather than feature-detect, for the reasons I explained
> above.

Not minimize the chance - but you'll certainly postpone the date when  
authors can use this for browser-detection with several years :)


-- 
                                                   Rijk van Geijtenbeek
                                                     Opera Software ASA
                                         http://my.opera.com/Rijk/blog/

"The most common way to get usability wrong is to listen to what users
say rather than actually watching what they do." - J.Nielsen
Received on Sunday, 13 December 2009 23:37:17 GMT

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