Here is another problem I met after installing the mmap branch fontconfig system-wide on my system. gnome-terminal doesn't seem to find fonts anymore. I haven't yet tried to follow all the fontconfig pattern manipulation done in vte, but it seems to trigger an incompatibility. A similar problem seems to affect the previews in the font capplet, which also seem to pick up a very small font size. The rest of the desktop seems to work fine. Matthias