Install wmdate by entering the following commands in the terminal:
sudo apt update sudo apt install wmdate
Description:
Calendar for window manager docking bars
wmdate produces a 64x64 pixel calendar for use in the docking bars of window managers. It was written specificly for Window Maker and goes well with docking bars that have a "clock-only" clock app such as pclock.
Homepage: http://solfertje.student.utwente.nl/~dalroi/wmdate/
Version: 0.7-4.1build1
Section: universe/x11