I am so very disappointed! I bought this to replace my K810 .. it is a perfect replacement... EXCEPT that I work in a dark room and the backlight switches off .. it is even worse in the dark ! duh! The K810, if wired could remain on all the time. WHY IS THIS SIMPLE OPTION NOT AVAILABLE ??!! so easy for you to implement, I see so many other people requesting it too . Very lazy & sloppy software work.. For several years 'it was coming' . I thought this latest software update might have it ... appalling lack of care for no good reason.