Ultimaker 2+ LED Lights on/off does not work/ different implementation

ThK

The gCode for turnig the LED lights on & off on Ultimaker 2+ are 'M42 S255' (full bright) to M42 S0 (off) in 254 steps. Unfotunately the "Light on/off) button seems to use another gCode. Where can the command string be edited (if editable) and would it be possible to add a slider in futute versiosn to support this opportunity?

Repetier

From 1.0.5 on this is editable in printer config->button commands.
Default commands are in firmware/marlin.xml for now in installation directory. You can edit it and replace them there.

Or you use the already existing gcode replacement capability in config->gcode->replacements where you replace the current command with your solution.