GridArrayEditor

In the attached image there is a list of colors labeled with a character

The character is the corresponding key on your computer you have to press to use that color

1 is the eraser

Pressing TAB resets the board

Press SHIFT and move the mouse to scroll

Hovering over the SizeX and SizeY buttons and inputting a value will change the game board size (tho it can be a bit finicky and you might have to re enter them occasionally)
(Also it resets the board)

When it says 2Long press backspace or it will send an error

When it says 2Short press any integer or it will send an error

Run this command in console when you are done with your edits:

open ~/Library/Application\ Support/com.radiotrophia.editor/Test.txt/

~radio