Ah, I see what you mean now. I use parallaxes. And I've been brushing in the lights in little cone shapes to keep with the top-down perspective. The light looks cut off over there because the light is part of the parallax, and not the overlay where the top edges of furniture look like it's in front of the player. I could move the lights to the overlay, but it'll increase its filesize.
(not sure if RM games' filesizes are really an issue nowadays, but I'm trying to keep it as low as possible)