Time intervals are saved into file on disk, they survive application restart.
Application adds icon into tray. Click on it with middle mouse button to pause stopwatch or timer.
python3 -m venv .venv # optional
source .venv/bin/activate # optional
pip install --upgrade pip
pip install -r requirements.txt # in Linux
pip install -r requirements-windows.txt # in Windows
python timer.pyw
In Windows you can double click timer.pyw
python stopwatch.pyw
In Windows you can double click stopwatch.pyw
https://www.geeksforgeeks.org/pyqt5-digital-stopwatch/ and https://www.geeksforgeeks.org/timer-application-using-pyqt5/
I used the code from geeksforgeeks, but heavily reworked it and added tray icon.
