park method
Implementation
int? park(ModalView modal) {
if (!modal.model.minimized) return null;
// Already Parked
if (parking.contains(modal)) return parking.indexOf(modal);
// Lot Full - Make Space
if (!parking.contains(null)) parking.add(null);
// First Empty Space
int space = parking.indexOf(null);
parking[space] = modal;
return space;
}