The ability to allocate a drawing order, that is, when using mark-ups it is rather annoying not being able to allocate on each individual object or to a group of object if it should appear on top of another object or in the back. This means that every time you select an object you might have to go back and re-select any relevant objects if they are supposed to appear in front (or on top) of the former object. In some cases this is not possible.