Too few screen brightness levels

[Konstantin Khlebnikov]

Gnome hotkeys for controlling screen backlight gives only 20 levels. Since modern notebooks have really powerful backlight only 2-3 lower steps are usable in the dark environment.

Maximum count of brightness levels is hardcoded to 20 in macro "BRIGHTNESS_STEP_AMOUNT":
https://gitlab.gnome.org/GNOME/gnome-settings-daemon/-/blob/master/plugins/power/gpm-common.h#L41
https://gitlab.gnome.org/GNOME/gnome-settings-daemon/-/blob/master/plugins/power/gsd-backlight.c#L899

For example, my thinkpad has 496 brightness levels:

cat /sys/class/backlight/intel_backlight/max_brightness
496

Hotkeys allows to set brightness 4, 28, 52, and the next step is 76 which is already too bright.