The Images used in Items in Process, Hotspot Popups (and maybe other components as well, haven’t checked…), why can’t they come from the Library?
It’s quite inconvenient to have to add them to an external repository and then adding them with their URLs rather than having those (not so special) images in the Library, just like all other images.
They can be added from the Library. If you already have one in place, just delete that image, and then when you click the +ADD button to add one, it gives you both options.