User Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:44.0) Gecko/20100101 Firefox/44.0 Build ID: 20160210153822 Steps to reproduce: Years ago I created a JavaScript demonstration using animated GIFs. Using the latest Firefox edition the animated GIFs aren't rendered correctly: When you move the mouse pointer across the background image, the animated GIFs are "jumping", i.e. they are occasionally rendered with an offset of approx. (-100px, -100px). Actual results: When you move the mouse pointer across the background image, the animated GIFs are "jumping", i.e. they are occasionally rendered with an offset of approx. (-100px, -100px). Expected results: The animated GIFs should be rendered steadily.

See attached short movie clip for a screencast demonstrating the issue.

Could you attach such a GIF to the bug report, please. (or provide a link to the GIF)

D'oh ... my fault. 8-0 I forgot to paste the link. Pardon me... Here it is: http://www.dashop.de/blog/en/dev/JavaScript/content/ImageShover/demo/ImageShover-Demo-Frame.html

Not a recent regression: https://hg.mozilla.org/mozilla-central/pushloghtml?fromchange=c8288d0c7a15&tochange=62d33e3ba514

regression window: https://hg.mozilla.org/integration/mozilla-inbound/pushloghtml?fromchange=4511d9ac1000&tochange=79624417d247