Function paint_speaking_ring 

pub fn paint_speaking_ring(
    scene: &mut Scene,
    transform: Affine,
    tile: RoundedRect,
    colour: AlphaColor<Srgb>,
    level: f32,
    theme: &Theme,
)

The ring a speaking participant’s tile wears over its picture: their colour, as strong as their voice is now (level, 0 to 1), a chrome rule thick on each side of the tile’s edge.