Article break wall tool and color on a single wall

[Monique]

Here are 2 attatchments; in the first one it shows what I mean by the 1 feet space at the wall s corner; the second one I can t paint the whole wall without any break wall...........

I try to change the snap to grid to 1/8" to reduce the stripe of the other wall color without again no succes. I attach a plan floor view, as I think it is more evident.
Again, thanks a lot,
Monique