Sudoku v2

This is an improved version of sudoku sidebar
https://addons.opera.com/en/extensions/details/sudoku-sidebar/
(PS: I also published that addon)
This new version's code was not copied/edition from the previous one,
so that means that this game's code is rewritten from scratch
Some features from the previous version has been removed
And there may be some things wrong, so tell me once you found bugs/glitches

More details are said in the picture/screenshot below