39168 - rename proprietary 'opacity' CSS property to '-moz-opacity'

Status: VERIFIED DUPLICATE of bug 3935

(Core :: CSS Parsing and Computation, enhancement, P3)

Description

[ekrock's old account (dead)]

Is there an easy way we can make -moz-opacity a valid synonym for the CSS 
property opacity for FCS, so that for FCS, reading or writing -moz-opacity just 
maps through to our opacity property?

Reason I request this enhancement: opacity is an under-development property in a 
CSS3 draft, but it's not finished yet. If we have our own opacity in FCS, 
developers write to it, and the final CSS3 draft specifies that opacity works in 
a different way than our initial implementation, we'll be forced at that point 
to (1) conform to CSS3 spec at the expense of breaking backward compatibility 
and existing content, or (2) not conform to the CSS3 spec.

If however we create -moz-opacity as a synonym for opacity in the first release, 
then we can tell developers to use -moz-opacity in their code for now. If the 
final CSS3 spec specifies that opacity works differently than our initial 
implementation, we'll be able to separate the two in our first CSS3-conformant 
release, making opacity conformant to the CSS3 spec while keeping -moz-opacity's 
behavior backwardly compatibile. 

Putting this in would be a nice insurance policy.

I apologize for not thinking of this earlier. If there's a way we can slip this 
in for FCS (if it's an easy hack, before 5/16 would be ideal! ;-> ) that would 
be great!

Comment 1

[Hixie (not reading bugmail)]

I would go even further and suggest we just _rename_ our "opacity" property 
to "-moz-opacity". Imagine if CSS3 does indeed introduce this property, but
defines it totally differently to us (worse case scenario, for example: 100% 
means totally transparent, and 0% means totally opaque). Now anyone 
using "opacity" in the standards compliant way will find their documents look
great in the next version of Mozilla, but DISAPPEAR in this version! Oops.

I'm pretty sure David will back me up on this; as this is one of his pet 
topics... ;-)

[marking CSS1 for future-compatability rules, CSS3 for 'opacity', CSS-MOZ for
our extension]

Comment 2

[Pierre Saslawsky]

Easy...
Pushed to M18 because PDT will never take that before.

Comment 3

[Johnny Stenback (:jst)]

There's more to this than just renaming this property in the style system, the
DOM CSS OM also has knowledge about the supported properties in the interface
CSS2Properties, and opacity is in there (in our interface, not in the DOM spec).
Should we either remove opacity from our DOM interface, or should we leave it
in and add -moz-opacity? Either way is easy to do, just let me know what you
think.

Comment 4

[Pierre Saslawsky]

Thanks for the heads-up, Johnny. We'll have to rename it in the DOM too.

Comment 5

[ekrock's old account (dead)]

*** This bug has been marked as a duplicate of 3935 ***

Comment 6

[Hixie (not reading bugmail)]

VERIFIED that this is a DUP of a more general bug.