Function paint_nav_section 

pub fn paint_nav_section(
    scene: &mut Scene,
    transform: Affine,
    text_renderer: &mut TextRenderer,
    theme: &Theme,
    face: &NavSectionFace<'_>,
)

Paint a section header: the title in Subheading, secondary ink; a collapsible section’s chevron while the pointer or focus is on it (or while it is collapsed, so a hidden section is never mistaken for an empty one); and its trailing action.