Some time after changing /etc/fonts/fonts.conf the problem completely returned, without any actions from me. Later I realized /etc/fonts/fonts.conf is not the one to blame here, so I can't understand why that edit to it happened to fix the problem temporarily.
Today I found the true reason of the bug. I happened to install fontconfig 2.9.0-7 together with package fonts-droid 20111207+git-1, containing /etc/fonts/conf.avail/65-droid-sans-fonts.conf which contains duplicated tags <test name="family">, That leads to "Fontconfig warning: ... Having multiple values in <test> isn't supported and may not work as expected". That problem described in bug http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=717688 Half a year ago I decided such warning is too annoying and deleted *some* sections from 65-droid-sans-fonts.conf. Now I see *some* were definitely superfluous, and new version of fontconfig just behaves different with that (actually semi-broken) config file. My fault. Now I restored Initial version of 65-droid-sans-fonts.conf and everything is OK. That's it. The bug should be closed. -- To UNSUBSCRIBE, email to debian-bugs-dist-requ...@lists.debian.org with a subject of "unsubscribe". Trouble? Contact listmas...@lists.debian.org