We create a GUI class to abstract common GUI needs (showing a message box, asking a question, ...) from the actual GUI backend.
We also create a Nexus class to manage the startup and lifetime of our main systems (Core, GUI, ...) instead of delegating that to Widget.
Eventually, Widget will only be in charge of the Desktop GUI and AndroidGUI of the mobile GUI. Nexus will overview the system and GUI will provide a clean platform-independant interface.
