Add a brightness slider for Ambient keyboard lighting mode

[circletone]

I love the ambient mode on the keyboard but a problem i keep running into is that isnt the brightest, i would appreciate it if the max setting at least boosts the luminescence a little more than just representing the spot on the screen. That would perfect this lighting mode for me atleast!

thank you for all your efforts serge, you've pretty much made this 2022 g15 the laptop of my dreams without the BS

[seerge]

@circletone hello,

Ambient mode uses same 3 backlight brightness levels as you have for other modes. You can control them with hotkeys or slider under Extra.

Don't forget - that Ambient reflects actual screen contents, so if you have something dark on the screen - keyboard will be dim, and when you open big bright white rectangle covering full screen - it will (obviously) become bright white :)