Turn off SUPER key during fullscreen apps

Is there a way to turn off the SUPER key during gaming sessions or fullscreen apps in general?

Introduction

The following script disables Super key if any X11 window is in fullscreen mode. It is meant to be added as a startup application , but also can run in a stand-alone mode.

Usage

To run the script manually it is sufficient to do :

python disable_super_key.py

In order to make the scrip start automatically upon login, consult How do I start applications automatically on login?

Obtaining the script source code

One could copy the script source from this answer, or obtain it via cloning my GitHub repository.

Instructions for those who have git :

1. cd /opt
2. sudo git clone https://github.com/SergKolo/sergrep.git
3. chmod -R +x sergrep

The script will be located in /opt/sergrep/disable_super_key.py

Script source code

#!/usr/bin/env python
#
###########################################################
# Author: Serg Kolo , contact: [email protected] 
# Date: August 1st , 2016
# Purpose: Disable Super key that calls Unity Dash, when any 
#          X11 window is in fullscreen state
# 
# Written for: https://askubuntu.com/q/805807/295286
# Tested on: Ubuntu 16.04 LTS 
###########################################################
# Copyright: Serg Kolo , 2016
#    
#     Permission to use, copy, modify, and distribute this software is hereby granted
#     without fee, provided that  the copyright notice above and this permission statement
#     appear in all copies.
#
#     THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
#     IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
#     FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
#     THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
#     LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
#     FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
#     DEALINGS IN THE SOFTWARE.
from __future__ import print_function
import gi
gi.require_version('Gdk', '3.0')
from gi.repository import  Gdk,Gio
import subprocess
import signal
import time
import sys

debug = False

def gsettings_get(schema,path,key):
    """ fetches value of gsettings schema"""
    if path is None:
        gsettings = Gio.Settings.new(schema)
    else:
        gsettings = Gio.Settings.new_with_path(schema,path)
    return gsettings.get_value(key)

def gsettings_set(schema,path,key,value):
    """ sets value of gsettings schema """
    if path is None:
        gsettings = Gio.Settings.new(schema)
    else:
        gsettings = Gio.Settings.new_with_path(schema,path)
    return gsettings.set_string(key,value)


def gsettings_reset(schema,path,key):
    """ resets schema:key value to default"""
    if path is None:
        gsettings = Gio.Settings.new(schema)
    else:
        gsettings = Gio.Settings.new_with_path(schema,path)
    return gsettings.reset(key)

def run_cmd(cmdlist):
    """ reusable function for running shell commands"""
    try:
        stdout = subprocess.check_output(cmdlist)
    except subprocess.CalledProcessError:
        pass
    else:
        if stdout:
            return stdout


def main():
    """ defines entry point of the program """
    screen = Gdk.Screen.get_default()
    while True:

        key_state = str(gsettings_get('org.compiz.unityshell', 
                                  '/org/compiz/profiles/unity/plugins/unityshell/', 
                                  'show-launcher'))
        active_xid = str(screen.get_active_window().get_xid())
        wm_state =  run_cmd( ['xprop', '-root', '-notype','-id',active_xid, '_NET_WM_STATE'])  

        if debug : print(key_state,wm_state)

        if 'FULLSCREEN' in wm_state:
            if "Super" in  key_state:    
                gsettings_set('org.compiz.unityshell', 
                              '/org/compiz/profiles/unity/plugins/unityshell/',
                              'show-launcher', 
                              'Disabled')

        else:
            if "Disabled" in key_state :
               gsettings_reset( 'org.compiz.unityshell', 
                                '/org/compiz/profiles/unity/plugins/unityshell/',
                                'show-launcher')


        time.sleep(0.25)


def sigterm_handler(*args):
    """ ensures that Super key has been reset upon exit"""
    gsettings_reset( 'org.compiz.unityshell', 
                     '/org/compiz/profiles/unity/plugins/unityshell/',
                     'show-launcher')

    if debug: print('CAUGHT SIGTERM')
    sys.exit(0)


if __name__ == "__main__":
    signal.signal(signal.SIGTERM,sigterm_handler)
    main()

Debugging

In case debugging is necessary , change line 32 from debug = False to debug = True and run the script from command line