I'm running Firefox on Arch Linux, and my support for international fonts is very limited.
This results in a lot of tofu on web pages:
Part of the Korean Wikipedia home page as an example -- although most interational fonts show up the same way.
Conversely, international fonts in the window's title bar do show up properly:
What I've tried so far is installing the a couple of the firefox-18n-* packages via pacman, and clearing my font cache using fc-cache -f /usr/share/fonts, but the issue's still around.
How can I get Firefox to render these international fonts properly?