I've got an email saying: "Looks like that APNG bug has returned in 3.0.7 ... Haven't tried 3.0.8 yet. https://bugzilla.mozilla.org/show_bug.cgi?id=420416 And I've got one more sample. Most likely the same bug." From the same guy who reported bug 420416. Attachment is attached. Will try to get more information from the reporter. I haven't reproduced it myself (am on 3.0.5 on Linux). Joe, do you want this one?

Reproducible in 3.1b3 as well.

More info from the reporter --------------------------- > Did you get a chance to try 3.0.8? Yes, and I tried 3.0.9 too. Both buggy. It started with 3.0.7: 3.0.6 - ok 3.0.7 - buggy 3.0.8 - buggy 3.0.9 - buggy > > I take it you're seing it on Windows? Yes. > > Also, that old image is in litmus test: https://litmus.mozilla.org/show_test.cgi?id=5213 > > I hope to add more details from you and trying it myself (I'm on linux). I remember that Glenn fixed it the last time by crearing prev_row buffer before decoding the next frame. I recently ran into the very similar looking problem in my little app and also fixed it by clearing prev_row buffer.

This works for me now, apparently fixed by the check-in of libpng-1.2.40 (bug #504805)

Artifacts are still present in Firefox 3.6.16

Works for me with the current nightly and with Firefox 24.0