see app.c, utils-sh.c, str-utils.c and common-utils.h

compile with:

gcc $(pkg-config --cflags gtk4) -o app app.c $(pkg-config --libs gtk4)

for shell commands backend.
for native backend, compile with:

gcc $(pkg-config --cflags gtk4) -o app app.c $(pkg-config --libs gtk4) -D__NATIVE