Mmm, I would say that's more a reflection of what the photograph was processed to look like, than what the actual, accurate backlight color is. Many photos used to show original Prontos with a baby blue backlight when they were all green to aqua green.

The "negative" illuminated version is how URC used to do their remotes, but they eventually gave up on the idea and went to standard black text / illuminated background. I think mainly because it makes the screen particularly hard to see in "dim" lighting conditions, where you want a bit of backlighting to help. There's no way to change how the backlight behaves on a particular remote, however.