change how an appointment looks like

        private bool isToggled = false;
        public MainPage()
        {
            InitializeComponent();
            calendar.OnMonthCellLoaded += Calendar_OnMonthCellLoaded;
        }

        private void Handle_Clicked(object sender, System.EventArgs e)
        {
            this.isToggled = !this.isToggled;
            calendar.Refresh();
        }

        private void Calendar_OnMonthCellLoaded(object sender, MonthCellLoadedEventArgs e)
        {
            if ((e.Date.Date.Day == 10 || e.Date.Date.Day == 11 || e.Date.Date.Day == 13) && this.isToggled)
            {
                var button = new Button();
                button.Text = e.Date.Day.ToString();
                e.View = button;
            }
        }