413141 - drop -moz-opacity alias

Status: RESOLVED FIXED

(Core :: CSS Parsing and Computation, defect)

Description

[Daniel.S]

The CSS 3 opacity property has been implemented since Gecko 1.7. However, the -moz-opacity alias was never removed. This seems odd, since other experimental properties have been removed after their standard equivalent was implemented.

According to MDC, use of -moz-opacity is deprecated since the implementation of the standard property. opacity is perfectly understood by Presto and WebKit (tested Safari 3 for Win).

Besides, best practice has always been writing proprietary and standard properties:

E {
 filter: alpha(50);
 -moz-opacity: 0.5;
 opacity: 0.5;
}

So, -moz-opacity should be removed, just like -moz-inline-block was when inline-block was finally implemented.

According to LXR some files are still using -moz-opacity, but I think this shouldn't be the problem here.

I have not heard of any reasons that speak against this. However, if I missed the reason please tell me.

Comment 1

[David Baron :dbaron: (⌚️UTC-4, no longer working on Mozilla)]

The reason I left it (in bug 93156) was that a lot of sites were using it.  That said, I agree I probably should have removed it (as I have done for later property renames).  That said, -moz-opacity is probably the most used -moz-* property on the Web by an order of magnitude.  I'm not sure whether I can justify doing it right before a release (increased risk of catching problems resulting) given the rather low benefits, though.

Comment 2

[Daniel.S]

I thought it was a bit too late for doing it now. 

Hm, just disabling it for Beta 3 is no option? Well, I better do not spam here. But good to know it's on your radar.

Comment 3

[Phil Ringnalda (:philor)]

http://mxr.mozilla.org/seamonkey/search?string=moz-opacity :|

Comment 4

[Dão Gottwald [:dao]]

The benefits of this would be interoperability (for pages using -moz-opacity but not opacity) and not further encouraging code bloat (for pages using both). The reasoning in bug 93156 was good for backwards-compatibility, but that's also four and a half years ago.

Comment 5

[Daniel.S]

(In reply to comment #4)
> The reasoning in bug 93156 was good for backwards-compatibility, but that's
> also four and a half years ago.

Yes. Most users of -moz-opacity also use the standard property as well as Microsoft's filter (which is disabled in IE8's no-quirks-mode to implement real opacity instead).
Presto and WebKit both support opacity as well now.

There are a lot of things going on this late in the cycle and some of them can break websites way more than this one. Besides -moz-pre-wrap was quickly removed in Bug #418543. This could/should be just as quick.

Sorry, I guess this can be interpreted as bugspam, didn't want to waste anyone's time.

Comment 6

[David Baron :dbaron: (⌚️UTC-4, no longer working on Mozilla)]

(In reply to comment #5)
> There are a lot of things going on this late in the cycle and some of them can
> break websites way more than this one. Besides -moz-pre-wrap was quickly
> removed in Bug #418543. This could/should be just as quick.

It wasn't actually.

Comment 7

[Daniel.S]

(In reply to comment #6)
> It wasn't actually.

Both could be done now, can't they?

Comment 8

[u88484]

Would probably be a good time to do this now before a beta because site developers should be checking out their sites with the beta...at least that is what I think.

Comment 9

[Daniel.S]

Attachment: trying to figure it out

I tried to figure out how this can be done. I probably failed because this is my first patch, but the attempt is more worth than another complaint.

Comment 10

[Daniel.S]

Attachment: Second Try

And this time it should actually apply. Sorry.

Comment 11

[David Baron :dbaron: (⌚️UTC-4, no longer working on Mozilla)]

Comment on attachment 339644 [details] [diff] [review]
Second Try

r+sr=dbaron, though this probably shouldn't land after the first beta

Comment 12

[Dão Gottwald [:dao]]

http://hg.mozilla.org/mozilla-central/rev/03796867bcd2

Comment 13

[Alfred Kayser]

How about removing also the -moz-outline aliases?

Comment 14

[Alfred Kayser]

http://developer.mozilla.org/en/CSS/-moz-outline:
"Starting with Gecko 1.8 (Firefox 1.5), the standard CSS 2.1 outline  property is supported as well. Use of outline  is preferred to -moz-outline. "

Comment 15

[Daniel.S]

(In reply to comment #13)
> How about removing also the -moz-outline aliases?

Filed Bug 458588 to achieve this.

Comment 16

[Eric Shepherd [:sheppy]]

The documentation has been updated.