This is very much a draft. It won't be published in this form but is presented only to compliment a thought of Digimath when discussing matters with me. See notes
In Peg Solitaire there was a query about Scratch color sensing. In this 'demo' I think that i am beginning to get some understandings of "sensing". Click the 1, Click it several times over. do exactly the same with the 7. Neither should exit the brown, but it does. It seems to me that it is the centre of the Sprite that is pertinent; with 1, the midpoint would land on the right border of brown. For the 7, a third click would supposedly place the midpoint in touch with the "brown" and so force the "else" on the fourth click.