Function reveal 

pub fn reveal<E>(
    element: E,
    id: impl Into<ElementId>,
    window: &mut Window,
    cx: &mut App,
) -> E
where
    E: Styled,

Fades and lifts an element into place once when it first mounts.

Keyed by id: a row that keeps its stable identity across renders plays the reveal only on its first frames, never on every content update.