macOS process stealing window focus

README.md

Sean Harding finally put into words an issue that I've witnessed for a while now on macOS Sonoma.

This is it: "Weird MacOS thing: the window I am working in will sometimes lose focus (without the app losing focus). Suddenly, and without any obvious cause. It will be as if no window has focus. Sometimes happens as often as every few minutes, sometimes doesn't happen for a long time. I can’t figure out any common variable. But it can be very disruptive. Has anyone else seen this? Any ideas?"

I've adjusted the Python script mentioned in the thread to work with Python 3.x that you can get with Homebrew for example.

This is what the output looks like:

> python3.11 find_focus_stealer.py
2024-03-08 17:20:34: iTerm2 [/Applications/iTerm.app]
2024-03-08 17:20:37: Safari [/System/Volumes/Preboot/Cryptexes/App/System/Applications/Safari.app]
2024-03-08 17:25:17: CoreServicesUIAgent [/System/Library/CoreServices/CoreServicesUIAgent.app]
2024-03-08 17:25:51: Safari [/System/Volumes/Preboot/Cryptexes/App/System/Applications/Safari.app]
2024-03-08 17:25:52: iTerm2 [/Applications/iTerm.app]

find_focus_stealer.py

#!/opt/homebrew/bin/python3

try:
    from AppKit import NSWorkspace
except ImportError:
    print("Can't import AppKit -- try installing it with:")
    print("pip install pyobjc")
    print("(Make sure your pip corresponds to your python install, e.g. python3.12 and pip3.12)")
    exit(1)

from datetime import datetime
from time import sleep

last_active_name = None
while True:
    active_app = NSWorkspace.sharedWorkspace().activeApplication()
    if active_app['NSApplicationName'] != last_active_name:
        last_active_name = active_app['NSApplicationName']
        print('%s: %s [%s]' % (
            datetime.now().strftime('%Y-%m-%d %H:%M:%S'),
            active_app['NSApplicationName'],
            active_app['NSApplicationPath']
        ))
    sleep(1)

This is the most annoying bug I've ever encountered in my life. I've had to deal with this for months. MacBook Pro 2018 i9 and now even a 2023 MacBook Pro M3 Max. Is there a way we can drill deeper to see what apps are calling the CoreServicesUIAgent? I know there's some correlation between the autoupdates some of the apps have and this bug as well but who knows.

Were you able to identify which app steals the focus? Because I cannot. The moment I started to log active window -- nothing steals the focus.

Also, I slightly modified your code to use logging framework:

from time import sleep
import logging

from AppKit import NSWorkspace

logger = logging.getLogger('focusstealer')

logger.setLevel(logging.INFO)
stream_handler = logging.StreamHandler()
stream_handler.setFormatter(logging.Formatter("%(asctime)s %(levelname)-8s %(name)s: %(message)s", "%Y-%m-%d %H:%M:%S"))
logger.addHandler(stream_handler)

workspace = NSWorkspace.sharedWorkspace()
active_app = None
while True:
    prev_app, active_app = active_app, workspace.activeApplication()
    if prev_app != active_app:
        logger.info('Focus changed to: %s (%s)', active_app['NSApplicationName'], active_app['NSApplicationPath'])
    sleep(0.5)

Were you able to identify which app steals the focus? Because I cannot. The moment I started to log active window -- nothing steals the focus.

Yep, I removed Carrot and never had the issue again.

Yep, I removed Carrot and never had the issue again.

Thanks. I have it installed, but it's not running in background. So it might be something else for me...

Update: indeed it was Carrot...