Function row_in 

pub fn row_in<E>(
    id: impl Into<ElementId>,
    theme: &Theme,
    index: usize,
    count: usize,
    element: E,
) -> AnimationElement<E>
where
    E: Styled + IntoElement + 'static,

The arrival one row of a menu-shaped list makes.

Opacity only, and deliberately so: a rise is a layout input, so a row that slid into place would publish a moving box while it travelled. The wave is Stagger::rows, whose window is capped however long the list is.