You know, at least on OS X, stk doesn't have a way to install itself so I had to guess which files were generated/needed (install.sh is blank). I ended up copying the .a files (these were generated when I followed the instructions to build "a library of objects" by running make from stk's source dir) to my /usr/local/lib/stk folder and the .h files to /usr/local/include folder. I'm pretty sure this is right but maybe I am missing something else here. Anyway both of those should be in my path, I was getting different errors when they weren't.
We're going to drive you crazy over software you didn't write, Ico! :)
Impossible to drive an already crazy man crazy ;-)
I think your problem is that your .a files should *not* go into a subfolder but directly into the /usr/local/lib folder.
Now that I also thought more about it, I think you do need to compile flext against stk, or otherwise munger1~ won't compile since it references flstk.h not Stk.h in its source.
Either way, aforesaid solution should fix this.
BTW, if anyone builds a binary for Win/PD, Mac/PD, or MacPPC/Max, please forward them to me so that I can include them in the distribution.
Best wishes,
Ico