Suggestion: make the brightness bar operational via shaders on screens without backlight
Feature summary
Suggestion: always keep the brightness bar in the top-right shell popup operational, and achieve this via shaders on screens without backlight. This has multiple uses: 1. on some screens (e.g. OLED), simply darkening can save a lot of energy. 2. there are other reasons to darken the screen, e.g. I use it a lot when I'm tired to make it easier on my eyes (for which the current night light functionality is way less suited because it's way too inflexible), 3. it's more consistent.
How would you like it to work
Brightness slider in top-right shell quick settings popup is always visible. For screens with no backlight controls, the RGB values of the outputted colors of the final image are adjusted via some sort of shader instead to achieve the dimming.