User Agent: Mozilla/5.0 (Windows NT 6.1) AppleWebKit/537.22 (KHTML, like Gecko) Chrome/25.0.1364.97 Safari/537.22 Steps to reproduce: I have a fixed element at the right-bottom of my page, style of element is {right: 1px; z-index: 6500; width: 310px; height: 190px; position: fixed; bottom: -190px;}. And the page has a vertical scroll bar. Then I make a CSS3 transition to change bottom property to 1px. The animation is ok，but the position of the element is unnormal after animation. It seems that the element ignore the width of the scroll bar, so that the right part of the element is behind the scroll bar, and about 17px become invisible. Actual results: But if I change width to auto, or do some action that can make the element re-render, it will come back to right place. U may try it ar http://i.qq.com/ Expected results: I think it is a bug of render engine or css3 transition engine since Firefox 19.(I try it in Firefox 18 and below, it works ok). The horizontal position of the element should not change when doing the vertical animation.

Can you provide/attach a reduced Testcase showing the Issue? Also you might be able to get a Regression Window using e.g. https://github.com/mozilla/mozregression/

You may try here. http://312294.ichengyun.net/css3_transition_ff19.html Click the bottom hide, then the bottom show. It the animation of bottom style, but the container element move to right, and the word 'me' cannot be seen. It become normal when anything trigger the re-render of the element.

Last good nightly: 2012-06-06 First bad nightly: 2012-06-07 Pushlog: http://hg.mozilla.org/mozilla-central/pushloghtml?fromchange=6338a8988917&tochange=7e4c2abb9fc9 => caused by Bug 157681 (disabled upto Firefox 18 and confirmes Comment 0).

Ignoring the width of the scroll bar? Sounds like bug 844178.

hi, Borism, will it be fixed?

Presumably, yes.

Fixed by bug 844178.