private void Emoji_OnItemClick(object sender, ItemClickEventArgs e)
        {
            var em = e.ClickedItem as Emoji;

            if (em != null)
            {
                EmojiSelectCompleted?.Invoke(this, em.Content);
            }
        }
        private void ListBox_SelectionChanged(object sender, SelectionChangedEventArgs e)
        {
            ListBox box = sender as ListBox;

            if (box.SelectedIndex < 0)
            {
                return;
            }
            Emoji em = box.SelectedItem as Emoji;

            box.SelectedIndex = -1;
            if (EmojiSelectCompleted != null)
            {
                EmojiSelectCompleted.Invoke(this, new EmojiSelectEventArgs(em.content));
                this.Close();
            }
        }