The RoboFont user interface is built with vanilla and defconAppKit, and adds several custom UI elements of its own. These RoboFont-specific objects are available via the mojo module – so you can use them to build your own tools, and to modify the way RoboFont looks and works.
mojo includes a lot more besides UI components: it gives access to all internal events and observers which form the backbone of the application. We’ll look into that in the next section, Tools with Observers.
mojo allows developers to unlock the full power of RoboFont.