Disable XF86Back and XF86Forward (browser back/forward on Lenovo Thinkpad)

My Thinkpad R500 has back/forward keys just about the direction keys, so on Firefox I keep losing entered text, accidentally.

How to disable these back/forward keys?

Excerpt from xev:

KeyPress event, serial 29, synthetic NO, window 0x5e00001,
    root 0xbc, subw 0x0, time 2375874, (1279,794), root:(1285,881),
    state 0x10, keycode 166 (keysym 0x1008ff26, XF86Back), same_screen YES,
    XLookupString gives 0 bytes: 
    XmbLookupString gives 0 bytes: 
    XFilterEvent returns: False
KeyPress event, serial 32, synthetic NO, window 0x5e00001,
    root 0xbc, subw 0x0, time 2377115, (1279,794), root:(1285,881),
    state 0x10, keycode 167 (keysym 0x1008ff27, XF86Forward), same_screen YES,
    XLookupString gives 0 bytes: 
    XmbLookupString gives 0 bytes: 
    XFilterEvent returns: False

Solution 1:

You can disable keys using the xmodmap command. For example, to disable XF86Back, run the following command:

xmodmap -e "keycode 166="

This sets the keycode 166 (Which is the keycode for XF86Back as you can see in the xev output) to nothing, which means it is disabled. To re-enable XF86Back:

xmodmap -e "keycode 166=XF86Back"

To disable both the Back and Forward keys automatically, create the file .xmodmap in your home folder and paste the following inside it:

keycode 166=
keycode 167=