I downloaded the Sun WTK 2.5 and managed to get a WTK demo project
to build using both a native JDK as well as a manually extracted
a Linux JDK (jdk-1_5_0_11-linux-i586.bin).  [The preverify binary
fails as it is linked against GLIB 2.6 though.]

So I suspect this problem has something to do with the directory
layout resulting from installing sun-jdk15/sun-jre15.

Doing a ktrace, it looks like the ktoolbar program tries to automatically
load tools.jar, but looks in the wrong place when using sun-j{dk,re}15:

 28802      1 java     CALL  stat64(0xb7649b78,0xb63fe6ac)
 28802      1 java     NAMI  "/emul/linux/usr/pkg/java/lib/tools.jar"
 28802      1 java     NAMI  "/usr/pkg/java/lib/tools.jar"
 28802      1 java     RET   stat64 -1 errno -2 No such file or directory

It's almost as if it's doing some test for whether some directory
contains a JRE, and manipulating the path otherwise (in this case,
stripping out `sun-1.5').  But I can't see anything in the ktrace
to indicate any tests.

Brian.

-- 
  Brian de Alwis | Software Practices Lab | UBC | http://www.cs.ubc.ca/~bsd/
      "Amusement to an observing mind is study." - Benjamin Disraeli