Function paint_severity_rail 

pub fn paint_severity_rail(
    scene: &mut Scene,
    transform: Affine,
    theme: &Theme,
    row: Rect,
    tone: Tone,
    inset: f64,
)

The rail a warning or a failure keeps beside its text, so a row’s status is scannable without taking another line; plain information carries no colour, so the rail means something wherever it appears.