When doing per-key lighting, do a highlight over what is going to be affected when the "save" izhit

Right now I want to make the side light one color and everything else another color. But most of the time when I make the side light one color, go one layer down and try to make every other key another color, I'll make the side light another color and I won't know why it did that even though I manually clicked on everything else. Some highlight or some other indicator beforehand would be useful to know when something is going to change would help.

If nothing else changes, at least make a highlight for the side light when that color zone is going to be affected by a save.