I recently tried to install
Espresso 2.1.2j on Ubuntu 16.04 64-bit. I had to manually give it the
path to tcl.h, that is, CPPFLAG=-I/[path to folder containing tcl.h].
built fine and it runs, but it says that it was unable to detect tk,
despite tk.h being in the same folder as tcl.h. It seems that tk is not required for it to run, but I'd like to get it working if possible. Is there another option I
need to specify to configure in order to have it find tk.h?