It would be nice if the GUI color slider screen wouldn't replace the arena map while adjusting the colors. As one who switches arenas a lot and sees lots of different maps - especially custom maps like the AvA and SEA offer - I find myself having to change colors to make map and flight icons easier to see. Because of some of the custom color palettes in use, I find changing certain GUI colors a must.
It's a pain to have to choose a color, exit the editing screen to see if that color now works, then go back and alter it again, exit to see if it's better, etc., etc.