public MainMenuViewModel(
     StageManager navigator,
     SessionState sessionState,
     AuthenticationService authenticator,
     ActivityService activityService,
     ActivityLauncher activityLauncher)
 {
     this.navigator        = navigator;
     this.sessionState     = sessionState;
     this.authenticator    = authenticator;
     this.activityService  = activityService;
     this.activityLauncher = activityLauncher;
 }
		public MainMenuViewModel(
			StageManager navigator, 
			SessionState sessionState,
			AuthenticationService authenticator, 
			ActivityService activityService,
			ActivityLauncher activityLauncher)
		{
			this.navigator = navigator;
			this.sessionState = sessionState;
			this.authenticator = authenticator;
			this.activityService = activityService;
			this.activityLauncher = activityLauncher;
		}