Currently for coloring the lister, we can choice only 1 background. That give us possibility to make look of lister in flat colors, which in compare with how modern amiga listers (filer on os4, ambient listers on mos) done, are a bit worse for readability.
I.e. all what second background should do, its just use next line in that color. I.e. one line in lister are background1, next line are background2 , and so on. So we add background2 in all the listers color options where background1 is present and can setup look of listers in modern way.
To show what i mean i attach 2 screenshots. One, how it now. And one, how it can be if we will add second background.