FULL PRODUCT VERSION :
java version "1.6.0_18"
Java(TM) SE Runtime Environment (build 1.6.0_18-b06)
Java HotSpot(TM) Client VM (build 16.0-b13, mixed mode, sharing)


OS VERSION INFORMATION :
Ubuntu-8.04 Desktop


EXTRA RELEVANT SYSTEM CONFIGURATION :
you need to Chinese/Korean/Japanese fonts installed on your system too, or fontconfig.properties will just point to non-existent font files.

STEPS TO FOLLOW TO REPRODUCE THE PROBLEM :
"java -jar Font2DTest.jar" with Java 6u18_b06_fcs build first on your path, and try to display the "Hangul Jamo" range (make sure you've actually installed the relevant fonts on your system first, or having the fallbacks won't help!).

EXPECTED VERSUS ACTUAL BEHAVIOR :
EXPECTED -
assuming you've installed Korean ("System" > "Administration" > "Language Support"), you'd expect to see Korean glyphs.
ACTUAL -
you can see many characters shows annoying little empty boxes :-(
and these characters display correct in jdk7 b77.

REPRODUCIBILITY :
This bug can be reproduced always.