The Core API is responsible for creating and mainting a tree of Dockables and DockStations, and
to distribute information and events between the different elements.
Many features have their roots in the Core API, but are properly configured and linked together with the Common API.
The strength of the Core API is its high level of abstraction, which allows clients to introduce new features, or tweak
existing ones. However, due to its abstractions the Core API is not really usefull for implementing applications.
If you just want to write an application, you should better use the Common API!