Disable hardware keys on Cyanogenmod 12.1 / SM-T800 (Samsung Galaxy Tab S) I've hated the hardware keys on my Samsung tablet since I bought it. Even after a year, I have to be careful not to brush the keys with my palm or else I'm suddenly exiting the book I'm reading or web page I'm viewing. 

I rooted the device to try and fix this, however the instructions I've found for enabling on-screen navigation (by editing build.props) either gave me a black bar with no navigation buttons or, on later Samsung updates, prevented my tablet from booting.

I finally got around to installing CyanogenMod 12.1 (cm_chagallwifi-userdebug 5.1.1 LMY49J 11fa7f9ea1), and I can enable on-screen navigation using the following command (taken from this question):

settings put secure dev_force_show_navbar 1


Now I need to disable the hardware buttons. Most instructions I've found indicate to edit /system/usr/keylayout/Geneic.kl and comment out the keys for HOME, BACK and MENU. I mounted /system as read-write and commented out keycodes 127 (Menu), 158 (back)and 172 (home). Yet after a reboot, my hardware keys are still enabled!

I also cannot disable the LEDs on the keys either. I found a script that attempt to do this sending a 0 to /sys/class/leds/button-backlight/brightness, which does not exist on my CM12.1 system. I can't find any other files under /sys/class/leds that seem to deal with the hardware button backlights either and there's nothing in the settings menu for them.

All I want is to be able to disable the hardware keys. Turning off the LEDs would be nice too.
I got an answer for this on this xda developers thread:

Isnt the key file in cm called something different sec_touchscreen.kl or something or other? 


Why yes ashyx, it is! In fact, it only has two entries! One is for the app switcher button and the other for the back button. After commenting out these lines, the buttons were disabled.

After digging through the settings, I also found that the button back lights are adjustable in this build of Cyanogen and was able to turn them off.