In /etc/fonts/fonts.conf there is a list of fonts to consider as valid replacements for generic "sans", "serif", and "monospace" aliases. Currently, DejaVu fonts are not listed there. It's a bug because Unicode coverage of DejaVu fonts is better than that of Bitstream Vera fonts, and glyphs present in both are exactly the same. Thus, DejaVu fonts are just a better drop-in replacement for Bitstream Vera. I am not sure about their priority. Maybe they can go just below Microsoft fonts - but that's just my opinion and personal preference.
Ubuntu Dapper (dev version before Ubuntu Linux 6.04) lists DejaVu in fonts.cooonf just after Bitstream Vera, with higher priority of the MS fonts. For Greek we are happy with this settings as long as a distribution uses DejaVu 2.3 or newer. Older versions of DejaVu with the current GNOME causes crashes, as shown at https://launchpad.net/products/pango/+bug/31910
Ubuntu Linux 6.06 has been released and it includes DejaVu 2.5 as the default font in fonts.conf. DejaVu works well for Greek and you get the same results with Vera for Latin/Latin-1 languages. DejaVu also supports Cyrillic.
It appears that the stock fontconfig does not provide a default fonts.conf file anymore. The configuration files are located in http://webcvs.freedesktop.org/fontconfig/fontconfig/conf.d/ and there is no file that specifies a list of fonts. The old "all-in-one" configuration file, is a dead file, http://webcvs.freedesktop.org/fontconfig/fontconfig/fonts.conf.in?hideattic=0&rev=None&view=log Is this correct? (fontconfig does not provide a default configuration file mentioning fonts)
The configuration file now includes both bitstream and vera. By default, bitstream vera fonts are preferred as they are more consistent and better hinted.
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