RE: [css3-conditional] Prefixing policy

[Simon Sapin:]
> 
> Hi,
> 
> As an implementer, I want to start playing with @supports. Is the
> "Experimental Implementations" section up-to-date to the current opinion
> of the group?
> 
> What is preferable?
> 
> 1. Add it prefixed: @-weasy-supports
> 2. Add it behind a user switch, disabled by default.
> 3. Add it in "experimental builds" but not in "release builds" (although
> WeasyPrint doesn't really have builds.) 4. Something else?
> 
>From informal conversations some implementers are not comfortable with ever 
doing #1 for this feature since that would imply copy/pasting large amounts 
of CSS multiple times. Entire stylesheets, really. 

As such some of us strongly prefer #2 and #3. 

(Similar thinking applies to CSS Variables, incidentally; although the
amount of data you have to copy may be smaller, it would defeat the feature's
very purpose).