Build Identifier: http://hg.mozilla.org/mozilla-central/rev/eccf45749400 Mozilla/5.0 (Windows NT 6.1; WOW64; rv:22.0) Gecko/20130311 Firefox/22.0 ID:20130311030946 This problem does not happen in IE, Opera and Chrome. Reproducible: always Steps to Reproduce: 1. Open testcase 2. Resize browser window Actual Results: The child element is re-positioned when I resize browser window Expected Results: The child elemnt should be positioned properly without resizing browser window Regression window Good: Mozilla/5.0 (Windows; U; Windows NT 6.1; en-US; rv:1.9a1) Gecko/20061207 Minefield/3.0a1 Bad: Mozilla/5.0 (Windows; U; Windows NT 6.1; en-US; rv:1.9a1) Gecko/20061208 Minefield/3.0a1 Bonsai log: http://bonsai.mozilla.org/cvsquery.cgi?treeid=default&module=all&branch=HEAD&branchtype=match&dir=&file=&filetype=match&who=&whotype=match&sortby=Date&hours=2&date=explicit&mindate=2006-12-07+00%3A00%3A00&maxdate=2006-12-08+03%3A00%3A00&cvsroot=%2Fcvsroot Suspected: Bug 300030

Strange, I can reproduce this in a new profile but not in my normal profile. In my normal profile it's correct even without resizing.

(Sorry, ignore the last comment. It was being affected by an extension adding something to the DOM.)

Dupping forward to bug with patch.