Created attachment 645573 [details]
User Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:14.0) Gecko/20100101 Firefox/14.0.1
Build ID: 20120713134347
Steps to reproduce:
Applied -moz-transition on an element that had opacity, left relative positioning, & -moz-transform:scale()
Details in jsFiddle here: http://jsfiddle.net/fCLaj/40/
As element animated, it repeatedly froze for milliseconds at a time while leaving temporary visual artifacts as it glitched through the animation.
Animation should have been visually smooth, transitioning opacity, scale, and position simultaneously.
I think it's a dupe of bug 775592.
(In reply to Loic from comment #1)
> I think it's a dupe of bug 775592.
That bug is also resolved if opacity is removed (removed with firebug to confirm).
This is somehow contingent on opacity...
(In reply to persona from comment #2)
> (In reply to Loic from comment #1)
> > I think it's a dupe of bug 775592.
> That bug is also resolved if opacity is removed (removed with firebug to
> This is somehow contingent on opacity...
I think there are 2 bugs in your testcase.
1) When I toggle to reduce the image from its large size (right position) to its small size (left position), there is a rendering glitch at the end as if there was a slight shift.
Look at my screenshot, especially the letters "O" & "y": http://i.imgur.com/qzRGl.png
It's a bug with opacity and resizing, see bug bug 745549.
2) A bug in the smoothness of the transition from left to right and from right to left.
It's bug 775592.
I tried your testcase with the latest Nightly and the rendering bug is gone.
I think it's fixed according to comment https://bugzilla.mozilla.org/show_bug.cgi?id=775592#c12