User-Agent: Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.8.1.5) Gecko/20070713 Firefox/2.0.0.5 Build Identifier: Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.8.1.5) Gecko/20070713 Firefox/2.0.0.5 According to CSS2.1, floats should overlap other non-positioned boxes in the normal flow, including it's backgrounds and borders. In the test case above, the div.fixed_bg got a background image and it's background-attachment was set to fixed, this resulted to the div to go on top of the float. Reproducible: Always Adding position:relative to the floats would cure this bug.

Buggy in the old Fx2, but fixed in Firefox 3 and higher.

Probably fixed by bug 317375.

A slightly simplified version of the reporter's testcase.

Did you test that the reftest failed in a build before the fix and passed afterwards? (You can test just by loading the pages in two tabs and switching between the tabs...)

I'm not sure if I understand you correctly. If you ask wether I've tested if bug 317375 was causing this, then no, I didn't test for this. If you're asking wether I've tested both, testcase and reference, in a buggy build and in a trunk build as well, then yes, I did (I always do).

Comment on attachment 355064 [details] [diff] [review] reftest [Checkin: Comment 7] r+sr=dbaron

Comment on attachment 355064 [details] [diff] [review] reftest [Checkin: Comment 7] http://hg.mozilla.org/mozilla-central/rev/6ece7e3224ca

Re-set checkin-needed (with whiteboard comment) if you want 1.9.1/... too.