I have experienced same problem, screenshot:
http://iki.fi/tero.koskinen/corrupted-netbeans-ant-output.png
It happens only with Netbeans. Other Java/Swing apps (like MagicDraw,
I am not sure it is a font problem. Now and then the console
output is fine and in the next moment the output is again plain squares.
Changing font preferences haven't helped me.
System:
OpenBSD 4.2-current (GENERIC) #553: Sun Nov 18 19:23:03 MST 2007
deraadt@i386.openbsd.org:/usr/src/sys/arch/i386/compile/GENERIC
netbeans-5.5p0
freefonts-0.10p0
ghostscript-fonts-8.11p0
jmk-fonts-3.0p0
sdl-ttf-2.0.8p3
terminus-font-4.20p0
jdk-1.5.0.13
--
Tero Koskinen - http://iki.fi/tero.koskinen/