I have some trouble to use function keys on Debian Stretch LXDE with my Acer Swift 1.
- Function keys work on Linuxmint 18 or Ubuntu (liveUSB).
- I can modify the file : /sys/class/backlight/intel_backlight/brightness with values between 0 and 96000 : it does change the brightness.
- I do not have a GUI-based app or applet to change the brightness, I can't find any.