How can I change the default font for a language

Samphan Raruenrom <[email protected]> Tue, 22 Feb 2005 19:20:00 +0700

Newsgroups	gmane.comp.mozilla.internationalization
Organization	Another Netscape Collabra Server User
Message-ID	<[email protected]>

Hi,

How can I change the default font for a language (e.g. Thai) in 
Mozilla/Firefox source?
IIRC, the default fonts for Thai are not very appropriate after fresh 
install.

Samphan.