Great! Found one bug

I clicked on a piece, which highlighted (that's nice)

I then decided I didn't want to move that piece, so I clicked on it again expecting the highlight to go away. Instead I stopped:
LEGAL% = -3: STOP: ' EXIT DO

Also, the display
White move:

It would be nice if, in addition to the highlight that display would be changed to
White move: e1-

and, when clicked again, the highlight goes away and the display changes back to
White move:

Mac