Pantheon Wallpaper (pantheon-wallpaper) is the simple and speedy wallpaper drawer used in Pantheon. It doesn't depend on any file manager or anything not related to drawing the wallpaper. Since it's lightweight, simple, and modular, it's very easy to use in other DEs as well. Even the settings it uses are app- and DE-agnostic; they're stored via dconf in /desktop/wallpaper, and any other wallpaper drawer or DE can readily use those settings.