Function segment_colors 

pub fn segment_colors(
    theme: &Theme,
    style: SegmentedStyle,
    selected: bool,
    hovered: bool,
) -> (Option<AlphaColor<Srgb>>, AlphaColor<Srgb>)

(fill, label) of one segment; fill == None means nothing is painted under it. On a SegmentedStyle::Segmented track the fill is the thumb.