Comment 5 for bug 1152377

> Also, when using "sudo /usr/lib/udev/keymap -i input/event3" (USB connection) it doesn't show the scan codes (e.g. the context menu appears),

Supposedly input/event3 is not the right device then. You can either find the right one based on names and type from "udevadm info --export-db | less", or just try each input/event1, 2, 3, etc. until you hit the right one.