Function layout_direction 

pub fn layout_direction() -> LayoutDirection

The app-wide layout direction (docs/localization): mirrors every horizontal placement in the place pass when [day_geometry::LayoutDirection::Rtl]. Resolved lazily from the DAY_LOCALE launch environment (so toolkits can read it before any UI exists); set_layout_direction (called by install_locales for the resolved locale) overrides. Fixed for the life of the process — switching locale at runtime does not re-mirror.