Here is a clock application for Linux/Unix done with Python and QT5. You need to install python3 and python-pyqt5 or similar to use this program. The program is frameless and places itself in the middle of the screen.
Without further ado, some screenshots.
#Digital Clock Copyright (c) 2017 JJ Posti <techtimejourney.net>
#Digital Clock comes with ABSOLUTELY NO WARRANTY;
#for details see: http://www.gnu.org/copyleft/gpl.html.
#This is free software, and you are welcome to redistribute it under
#GPL Version 2, June 1991
If needed make python files executable: chmod +x filename.py
Run with: python filename_location.py