keep_minimized.py

from gi.repository import GdkX11,Gdk
import subprocess
import time

def run_sh(cmd):
    # run shell commands
    p = subprocess.Popen(cmd, shell=True, stdout=subprocess.PIPE)
    out = p.stdout.read().strip()
    return out 

def get_window_xid():
    for item in run_sh("xwininfo -int").split("\n"):
        if "Window id" in item:
           return item.split()[3]

user_selection = get_window_xid()
screen =  Gdk.Screen.get_default()
while True :
    time.sleep(0.25)
    active_window = screen.get_active_window()
    if int(active_window.get_xid()) == int(user_selection):
        active_window.iconify()