Macro window 

macro_rules! window {
    ($width:expr, $height:expr, $name:tt) => { ... };
    (?$width:expr, $height:expr, $name:tt) => { ... };
    ($width:expr, $height:expr, $name:tt, $color:tt) => { ... };
    (?$width:expr, $height:expr, $name:tt, $color:tt) => { ... };
}

Initializes a WindowContainer. Optional background color. Begin with ? to unwrap.