Reproducible on the latest Aurora (BuildID: 20140313004000): Mozilla/5.0 (X11; Linux i686; rv:29.0) Gecko/20100101 Firefox/29.0 Reproducible on the latest Nightly (BuildID: 20140313030202): Mozilla/5.0 (X11; Linux i686; rv:30.0) Gecko/20100101 Firefox/30.0 Steps to reproduce: 1. Launch Nightly/Aurora. 2. Resize browser from left to right. Expected results: Icons from Navigation toolbar are pushed to overflow menu. Actual results: Search bar and Bookmark star is overlapped. Notes: 1. This is Mac OS X only 1. This issue is a regression m-c Last good revision: d01bf8596d3b (2014-03-08) First bad revision: 21f293fc8d34 (2014-03-09) Pushlog: https://hg.mozilla.org/mozilla-central/pushloghtml?fromchange=d01bf8596d3b&tochange=21f293fc8d34 m-i Last good revision: c7d86e2ddfea First bad revision: e9e0d0ae787b Pushlog: https://hg.mozilla.org/integration/mozilla-inbound/pushloghtml?fromchange=c7d86e2ddfea&tochange=e9e0d0ae787b

I can't reproduce this anymore on a build with bug 983632 fixed. Please undupe if you can.