Function tile

fn tile(
    ui: &mut Ui,
    id: Id,
    payload: DragPayload,
    selected: bool,
    tag: &str,
    name: &str,
    tint: Color32,
    palette: &Palette,
    art: Art,
    w: f32,
) -> Response

Gallery cell: a picture box with the kind tag in its corner and the name under it. Shared by the asset gallery and the reuse sections; the caller decides what the click means.