How to remap the Context Menu key to the Super key

Use xev to find the keycode for the key you want to remap. For example if I press Menu key it tells me that that is keycode 135.

Next in my ~/.xmodmaprc file, I add a line like this:

keycode 135 = Super_R

... to make it the right hand windows key. Then all that remains is to activate the key remaps. This usually happens automatically on login to your x session, but if your Desktop Environment doesn't do that you can run it manually as xmodmap ~/.xmodmaprc from a command line or whatever script gets run when you login.

I don't know what system you use, but if it is quite modern login as root, go to

/usr/share/X11/xkb/keycodes

Copy (make a backup) evdev file. Edit it. Find the line with Menu Key and change its alias to super key (left or right) e.g. change

alias <MENU> = <COMP>;

to

alias <MENU> = <SUPR>;

Logout, login (X11 has to be restarted), enjoy your new keyboard.