This is a metabug for tracking the bugs needed to make our CSS transitions support complete enough to ship. It is a tracking bug only; technical issues should not be discussed here.

And please note that I'm being pessimistic about requirements: if there's doubt, I'm adding a bug as a dependency of this bug, even though I might remove it later.

Also need to get a bug on file for animating between 'auto' values of various properties and numbers (preferably implemented on top of calc()).

We have documentation for CSS transitions. I need someone to please review these to let me know if they're accurate; it's been a while since the stuff was written and I don't know if there have been changes to the implementation: https://developer.mozilla.org/en/CSS/CSS_transitions https://developer.mozilla.org/en/CSS/-moz-transition https://developer.mozilla.org/en/CSS/-moz-transition-property https://developer.mozilla.org/en/CSS/-moz-transition-duration https://developer.mozilla.org/en/CSS/-moz-transition-timing-function https://developer.mozilla.org/en/CSS/-moz-transition-delay

it seems that we don't support clip in transitions. Should I report it as a separate bug or is it intended?

'clip' should work, though we can't transition from clip:auto to some other 'clip' (not fixable) and probably not from 'auto' values within rects to other values (probably fixable)

yeah, I hit the "from auto values within rects to other values" case. Should I report that one?

Sure; it's definitely worth having a bug on, though it probably won't happen for 4.0.

filed as bug 608591

@Zbigniew Braniecki Shouldn't this also depend on the bug 608591?