Subscribe to X11 PropertyChange events

x11_events.py

"""
Subscribe to X11 PropertyChange events and print "Window Changed!" when a
_NET_ACTIVE_WINDOW property has been changed.

Unfortunately no event is received events when _NET_WM_NAME is changed so this
would only partially solve https://github.com/dictation-toolbox/aenea/issues/103

You'll have to `pip install python-xlib` to run this script.

(Tested with the Cinnamon 2.2.16 desktop)
"""

import Xlib
from Xlib.display import Display
import Xlib.XK
from time import sleep

display = Display(':0')

NET_WM_NAME = display.intern_atom('_NET_WM_NAME')
NET_ACTIVE_WINDOW = display.intern_atom('_NET_ACTIVE_WINDOW')

root = display.screen().root
root.change_attributes(event_mask=Xlib.X.PropertyChangeMask)

print('Running...')
while True:
    while display.pending_events():
        event = display.next_event()
        if type(event) == Xlib.protocol.event.PropertyNotify:
            atom_name = display.get_atom_name(event.atom)
            if atom_name == '_NET_ACTIVE_WINDOW':
                print 'Window changed!'
            elif atom_name == '_NET_WM_NAME':
                print 'Window name changed!'
    sleep(0.1)

Hi,
thanks for nice snippet! Do you have clue why not all windows report wm_name? For me Opera, HipChat and some other apps return empty string on get_wm_name()