Struggeling with nice UI I learned a lot from guidelab.py (rather nice!), which meanwhile has grown to my guidelab_paint.py ... where the latest version can put checker pieces on a checkboard, two lines in a file first for black stones, second the white stones.
Now busy to make use of it in Gimp as a checker-beginner.
The plugin for that is already on the way (see other thread of me

)
That UI is a very minimal Dialog-window!
Scrapped the checker code (mostly) it became this:
Attachment:
gtkMINI_1feb.zip
Please have a look and Comments are very welcome!
After extracting into a plugin-directory where Gimp looks the plugin
shows as GTK ==>MINIdialog
Greets
Peter
It will be interesting to see where it goes from here.