The new spawn eggs are a fantastic edition. The only problem is the mobs with the eggs do not have their middle click function connected to the eggs themselves. When middle clicking a Cat, Wither Skeleton, Mule, Donkey, Elder Guardian, Stray, Husk, and etc., they give you the basic mob eggs they correspond to, such as Wither Skeleton and Stray gives you Skeleton Egg, Husk gives you Zombie, Elder Guardian gives you Guardian, Cats gives you Ocelots, and Donkeys and Mules gives you Horses.