public static Task<string> Display(string title, string text = null)
        {
            Popup popup = new Popup();
            popup.Height = 240;
            popup.Width = 480;
            popup.VerticalOffset = 100;
            popup.VerticalAlignment = VerticalAlignment.Center;
            InputDialog dialog = new InputDialog();
            dialog.lblTitle.Text = title;
            dialog.txtContent.Text = text ?? "";
            popup.Child = dialog;
            TaskCompletionSource<string> tcs = new TaskCompletionSource<string>();
            dialog.btnCancel.Click += (s, ea) =>
            {
                tcs.SetResult(null);
                popup.IsOpen = false;
            };

            dialog.btnOk.Click += (s, ea) =>
            {
                tcs.SetResult(dialog.txtContent.Text);
                popup.IsOpen = false;
            };

            popup.IsOpen = true;
            return tcs.Task;
        }
        public static Task<bool> DisplayYesNo(string text)
        {
            Popup popup = new Popup();
            popup.Height = 240;
            popup.Width = 480;
            popup.VerticalOffset = 100;
            popup.VerticalAlignment = VerticalAlignment.Center;
            InputDialog dialog = new InputDialog();
            dialog.lblTitle.Text = "Question";
            dialog.txtContent.Text = text;
            dialog.btnCancel.Content = "No";
            dialog.btnOk.Content = "Yes";
            popup.Child = dialog;
            TaskCompletionSource<bool> tcs = new TaskCompletionSource<bool>();
            dialog.btnCancel.Click += (s, ea) =>
            {
                tcs.SetResult(false);
                popup.IsOpen = false;
            };

            dialog.btnOk.Click += (s, ea) =>
            {
                tcs.SetResult(true);
                popup.IsOpen = false;
            };

            popup.IsOpen = true;
            return tcs.Task;
        }