Function color_row

fn color_row(
    ui: &mut Ui,
    label: &str,
    ov: &mut Option<[u8; 3]>,
    fallback: Color32,
) -> bool

One overridable colour: checkbox turns the override on/off, the button edits it while on (shown at fallback — today’s derived colour — while off, so turning it on starts from what’s in effect).