Gustaf,
to be sure, i just built xotcl 1.4.0 against 8.4.13, and it worked without a glitch.
thanks for making the effort! I started now with the switches from the oacs wiki docs you pointed me to:
./configure --enable-threads --prefix=/usr/local/ns \ --exec-prefix=/usr/local/ns --with-tcl=/tmp/tcl8.4.13/unix
and it shows that "--with-tcl=" arg did the trick on my machine. The TCL config files are identical (diffed), nevertheless. If I can find some more time, I'll try to track exactly whats going on, for now, it compiled as expected in the first run.
Thanks! Bernd.