Color picker for Background Color

Simple, but powerful:

Currently there is the option to select a background in 10 differenct colors. I know it is possible to just upload the desired color as a wallpaper, but a color picker to select the wanted color seems to me like the most appropriate solution, giving the user the most flexibility, while being a simple feature to implement.

Extra: Maybe a feature that also supports custom gradients later in the future would be a nice addition.