Macro ui_component 

macro_rules! ui_component {
    ($($ty:ty),+ $(,)?) => { ... };
}

Registers .yui components (types implementing ui::component::Component) when the mod’s library loads, so screens can use <Name …/> and Yog-IDLE’s designer host can draw them. The code yog build generates from a <Component> .yui calls this — mods don’t write it themselves.