public ShellViewModel(SubViewModel subViewModel, IFlyoutManager flyoutManager, IDialogManager dialogManager) {
            _subViewModel = subViewModel;
            _flyoutManager = flyoutManager;
            _dialogManager = dialogManager;

            Title = "Hello world";
            _subViewModel.SomeText = "Some text";

            _showFlyoutCommand = new RelayCommand(OnShowFlyout);
            _showDialogCommand = new RelayCommand(OnShowDialog);
        }
        public ShellViewModel(SubViewModel subViewModel, IFlyoutManager flyoutManager, IDialogManager dialogManager)
        {
            _subViewModel  = subViewModel;
            _flyoutManager = flyoutManager;
            _dialogManager = dialogManager;

            Title = "Hello world";
            _subViewModel.SomeText = "Some text";

            _showFlyoutCommand = new RelayCommand(OnShowFlyout);
            _showDialogCommand = new RelayCommand(OnShowDialog);
        }