Function paint_follow_frame 

pub fn paint_follow_frame(
    scene: &mut Scene,
    transform: Affine,
    area: Rect,
    colour: AlphaColor<Srgb>,
    openness: f32,
    theme: &Theme,
)

The frame round the work while following someone: their colour, a chrome rule either side of area’s edge at the tile radius, as present as the follow is (openness, 0 to 1).