public WindowBottomBarPartViewModel(
            IVersionService versionService,
            IEventService eventService,
            IViewModelSource viewModelLocator)
        {
            _eventService = eventService;

            // build view models for child user controls
            UpdateControlViewModel       = viewModelLocator.GetExisting <UpdateControlViewModel>();
            GameControlViewModel         = viewModelLocator.GetExisting <GameControlViewModel>();
            EventsButtonControlViewModel = viewModelLocator.GetExisting <EventsButtonViewModel>();

            // setup vars
            VersionString = versionService.GetLauncherVersion().ToString();
        }