public Tray()
        {
            AddOneCommand = new RelayCommand(args =>
            {
                var recipe = args as Recipe;
                SelectedCategory.Add(recipe);
                (AddOneCommand as RelayCommand)?.OnCanExecuteChanged();
            },
                                             (args) => SelectedCategory.CanAcceptMore);

            RemoveOneCommand = new RelayCommand(args =>
            {
                var recipe = args as Recipe;
                SelectedCategory.Remove(recipe);
                (RemoveOneCommand as RelayCommand)?.OnCanExecuteChanged();
            });
            RemoveCommand = new RelayCommand(args =>
            {
                var recipe = args as Recipe;
                SelectedCategory.Remove(recipe, recipe.NumOfServings);
                (RemoveCommand as RelayCommand)?.OnCanExecuteChanged();
            });
            InitializeComponent();
        }