iup::elements!

macro_rules! elements {
    () => { vec! [] };
    ($($elem:expr),+,) => { elements! [ $($elem),+ ] };
    ($($elem:expr),*) => { vec! [ $($crate::element::Handle::from($elem)),* ] };
}

Makes a Vec of Element trait objects.

This actually uses the Handle wrapper instead of Element due to the Sized requirement.

This should be passed to functions that expect a list of elements in the constructor.