making incompatible changes (was Re: [css-color][css-transitions] Interpolation between currentcolor keyword and actual color value)

On Friday 2016-04-22 12:25 -0700, Tab Atkins Jr. wrote:
> The currentcolor change was finally resolved on in the May 2012
> Hamburg F2F, just short of *4 years ago*; it was added to the errata
> some time after that.  Implementations have definitely had their
> chance to check that this is safe.
> 
> Since they've instead drug their feet on making the change, it's
> possible we might only *now* discover that it's unsafe, but I don't
> think it's reasonable to blame the *CSSWG* for that. ^_^

I think that's because the way we've made incompatible changes was
not acceptable.

I think we should only agree to make incompatible changes
conditional on getting positive feedback within a relatively short
time period, such that the change reverts if we don't get such
feedback.  This will avoid getting into such an inconsistent state
where we spec things that depend on a change that is incompatible
with reality.

I don't think it's OK for the group to presume that giving such
feedback is a priority for implementations.

-David

-- 
𝄞   L. David Baron                         http://dbaron.org/   𝄂
𝄢   Mozilla                          https://www.mozilla.org/   𝄂
             Before I built a wall I'd ask to know
             What I was walling in or walling out,
             And to whom I was like to give offense.
               - Robert Frost, Mending Wall (1914)