The new "multi-lingual font configuration" support in Tiger (aka JDK 5.0)
provides for fallback fonts that aren't considered part of the core set
of font required to support a user's environment based on regional settings.

The fallback fonts that may be chosen are specified in the JDK's
fontconfiguration.properties files.

These chosen fonts are ones we have selected as being the most suitable,
based on quality, coverage, etc.

This works fairly well on Solaris and Windows where in almost all cases
these fonts will be those from the O/S install, and are known and predictable.

On Linux it may work less well, because there is both variation and
unpredictable change across versions and releases.
So whilst JDK would continue to prefer the fonts we specifically identify
for fallback fonts, if they aren't present then it may be worthwhile to
locate a suitable alternative from the installed fonts.
I believe that (at some cost) we could leverage libfontconfig in 2 ways
(not to be confused with the unfortunately similar JDK term of
font configuration files)

1) It could provide a less expensive mechanism for locating the preferred
font, in case it has moved. This requires augmentation of the  Linux
font configuration files to specify font face name, as is already required
in some cases to support TTC files. Note that additional such strings will
increase the size of the font configuration files.
[[This usage fontconfig could also be considered as a better way to locate
a "moved" font file for core fonts too. ie better than the current mechanism
of matching XLFDs to filenames. XLFDs are arguably largely historical in modern
Gnome (ie GTK) apps as they don't use X11 for text. So ultimately the
requirement for XLFDs in font configuration files may be obsoleted.]]

2) In the event that #1 fails, then libfontconfig can be used to locate
a different font which supports the same script. A way of selecting the best
match may need some experimentation.