ref: cd711ec1346a827a8115f5bda7b5da57f9e7c181 dir: /sys/lib/kbmap/mouse-fn/
# Use F1, F2, F3, F4, F5 as mouse buttons (useful on laptops) 0 59 M1 0 60 M2 0 61 M3 0 62 M4 0 63 M5