The UI is completely disconnected from the business logic code. In fact, the business logic code is done in AppDevPoint and the UI is done in the native compiler of the platform.
Since the business logic code is transversal to all builds, any change to it must be reflected on the native compiler, so generating builds automatically updates all native projects in a single action.
This degree of modularity allows to split the development among several resources, for instance, one could be coding the business logic (AppDevPoint) while other could be designing the application for Android (Eclipse) and a third person could be doing the design for Windows Phone (Visual Studio, C#), and so on.
Since AppDevPoint does not generate executable files it cannot be called a compiler. It is more like a transcompiler (or transpiler) since it translates some sort of code into other types of code.
Internally, the business logic code is stored in XML files, totally independent from the native language of the platform.