User Agent: Mozilla/5.0 (X11; Linux x86_64; rv:9.0a1) Gecko/20110919 Firefox/9.0a1 Build ID: 20110919030912 Steps to reproduce: 1. Go to http://fr.wikipedia.org/wiki/Classification_des_groupes_simples_finis#Une_classification_de_deuxi.C3.A8me_g.C3.A9n.C3.A9ration 2. See the fifth word “extrême” Actual results: The ê is badly rendered. The same issue occurs on â, so I assume this the case with the other letters. Expected results: It should be rendered normaaly.

Mozilla/5.0 (Windows NT 5.1; rv:9.0a1) Gecko/20110918 Firefox/9.0a1 Works on winXP

The issue seems to occur only with FreeSans, and by only I mean not with DejaVu Sans. Note that FreeSans works normally on others Qt and GTK apps.

Mozilla/5.0 (X11; Linux x86_64; rv:9.0a1) Gecko/20110918 Firefox/9.0a1 Works for me on Ubuntu 11.04 I set the font to Free Sans medium and 10 for each of the options under the Font category in Appearance. The text from the page provided in Comment 0 was rendered correctly. Have you attempted to start in safe mode or with a clean profile and see if the issue occurs?

Mozilla/5.0 (X11; Linux x86_64; rv:9.0a1) Gecko/20110918 Firefox/9.0a1 Actually I can reproduce the issue on Ubuntu 11.04. Thanks for reporting and sorry about the rush with the previous comment, Loïc. STR: 1. Set Preferences/Content/Fonts and Colors-Advanced/Sans-serif to Free Sans. 2. Load the webpage provided in the URL. The circumflex e and the letter next to it seem to overlap each other. Last good nightly: 2011-03-24 First bad nightly: 2011-03-25 Pushlog: http://hg.mozilla.org/mozilla-central/pushloghtml?fromchange=741701875aec&tochange=e11c2f95f781

I believe this is caused by an error in the font. See bug 644857 comment 12.