Figuring Out the Font System on Linux Desktops?

koreth asks: "Last year I switched to Debian sarge on my office desktop machine. For the most part it's been great, but I can't seem to wrap my brain around fonts. For example, my favorite programming font is Sheldon Narrow. After running it through a few conversion tools and copying it to various font directories, I was able to start using it in xterm. But no sign of it in Konsole, despite running it through KDE's font installer tool. A few times I've installed new fonts that appear in the font lists of GNOME apps but not KDE apps or vice versa, and it's unclear to me how either environment's fonts interact with what I see when I run 'xlsfonts'. I have yet to find any documentation describing how either GNOME or KDE decides which fonts it likes. And then there's Debian's 'defoma', which seems to interact with everything somehow. Are there any good resources out there for learning what's going on under the hood of a modern Linux desktop environment's font subsystem?"