colourselect2 is just a slightly modified version and drop-in replacement for Lorne White's colourselect.py custom control found in wxPython.
Click here to download the code. It is a compressed file containing these three python files: colourselect2.py (the control itself), colourselectdemo.py (the wxPython demo modified to show the original and this new control side by side) and run.py (a copy of the run.py file found in the wxPython Demo).
To run it, type
python3 spinctrl.py
Tested on wxPython 4.0.4
(gtk3) on Python 3.7.3 on Raspberry Pi OS
and on wxPython 4.0.7p2
(gtk2) on Python 3.5.2 on Mint (Mate). The original
colourselect was written by Lorne White; run.py was written by
Robin Dunn. The files mentioned here are distributed under the wxWidgets
Licence.