Similar problem here. I am completely green to Arduino/IDE/etc.
I have IDE 1.18.10 and I have all in 'antenna_analyzer_p3.ino' First line is #include <glcd.h>. glcd.h is in libraries and 'ks0108_Arduino.h is in glcd subfolder.
Anyway, I try to compile and keep getting the error- 'btnDown' was not declared in this scope. Things just stop from there. Any ideas?