Floor settings mixed up.

When I try to make a custom theme with my own floor image, having "Use my Windows background as the floor" unchecked made my windows background the floor and not having it checked made the image that I selected the floor. No issue with this when using a premade theme. It's not that big of a problem and doesn't effect usability, but it is slightly confusing at first.

EDIT: "Use my Windows background as the floor" works properly when at least one other change has been made (ie: front wall image changed, or wall lighting applied). However, afterward, it goes back to not working.