For a client, there was a request for customizing the color picker for RTF fields. They wanted other/extra presets to add some often used colors from their Style Guide as buttons. This saves the Content Manager a lot of work and prevents them from choosing the wrong color (he/she has to remember the exact hex codes).
Proposal: split the color picker dialog in two render modes (foreground and background color). Make a config file for both render modes. It should contain color presets with button text and color code. And document it as a customizable GUI extension point.