Comment 4 for bug 86689

I've only just started using Feisty Fawn, and ran into this concern as well. It took a while before I traced it down.

New versions of fonts are also included as part of the updates in a new Ubuntu release. In Edgy, the version of ttf-dejavu included in 2.7-2. In Feisty, 2.14-2 is included. I checked the DejaVu project page to find out what changes were made in between those two versions, and noticed an important change from 2.8 to 2.9. Starting in the 2.9 version, the "condensed" and "extralight" families of the DejaVu font were now treated as styles and not families. This means that from that version on, there is no longer a separate file for "DejaVu Sans Condensed", but rather, it now appears as a style under "DejaVu Sans".

Apparently, Firefox is unable to extract the font style, thus the GUI elements in the application use "DejaVu Sans" instead. If you also wanted your default content font to be "DejaVu Sans Condensed", you wouldn't be able to find it under Edit > Preferences > Content > Fonts & Colors > Advanced. Editing the settings in about:config will work to change the default content font, but the GUI fonts will still not be "DejaVu Sans Condensed".

I wanted a solution to this problem, and thus, what I did was to download the 2.7-2 deb of the ttf-dejavu package from Ubuntu packages (http://packages.ubuntu.com/edgy/x11/ttf-dejavu). I know downgrading is generally not recommended, but I wanted a fix. I haven't noticed any problems in using 2.7-2 thus far.

I take this as a Firefox limitation, since the changes in the DejaVu font state why such reclassification was made. Hopefully this could be fixed in future releases.

P.S. By the way, this font concern also applies to the 2.2 version of OpenOffice that is part of the Feisty Fawn release.