A LightDictionary<Type, Controller> object representing a Controller collection.
Each Frame (and Window, consequently) has a Controller collection. To access, add or remove a Controller from this collection, use members of the LightDictionary<Type, Controller> object (Key, Value, Next, AddItem, FindItem, etc.), which is returned by the Controllers property. To access a particular Controller, use the GetController<ControllerType> method.