Using your keys.bi and window9.bi solved all the compile errors.
Then had to copy the buttons folder to the source folder. (path in window9.bi is from project folder)
Now I just have to chase down missing libraries.
Regardsld: cannot find -lgtk-x11-2.0
ld: cannot find -lgdk-x11-2.0
ld: cannot find -lgio-2.0
ld: cannot find -lgobject-2.0
ld: cannot find -lglib-2.0
ld: cannot find -lgmodule-2.0
ld: cannot find -lcairo
ld: cannot find -lpango-1.0
ld: cannot find -lgdk_pixbuf-2.0
ld: cannot find -lpangocairo-1.0
ld: cannot find -latk-1.0
ld: cannot find -lz
ld: cannot find -lGLU
ld: cannot find -lscintilla
linking failed: 'ld' terminated with exit code 1
Compilation failed.
Edit: You must have made a few links to other libraries, as some of these are not available but included in others.
When I try others, Mint 19.3 tells me I already have the latest. ?
EDIT: Resolved all except lscintilla.so which when installed creates an error when starting program:
I even changed Window9.bi to #define __USE_GTK3__ which was remmed out, but to no avail../fbdebugger_new: error while loading shared libraries: libscintilla.so: cannot open shared object file: No such file or directory