A base class for fragments that contain the contents of frontend panels. Typical IVI fragments are responsible for creating a layout and linking it to a ViewModel. The viewModelClass is responsible for the business logic and the state of a fragment. This is because, unlike fragments, ViewModels are persistent across configuration changes.
An IviOnBackPressedCallback that can dispatch on back presses to other IviOnBackPressedCallbacks. It is disabled by default and enabled when any of added callbacks are enabled. The last added callback that is currently enabled is called to handle the back press.