private void btn_seleccionar_Click(object sender, RoutedEventArgs e)
        {
            //obtener el contenido de la letra y mostrarla en el textview
            card_letra.Visibility = Visibility.Visible;
            Entidades.e_letras letra = new Datos.Da_letras().ObtenerLetra(lbl_id_evento.Content.ToString());

            //Creamos un nuevo tab para la cancion seleccionada
            TabItem aTabItem = new TabItem();

            aTabItem.Name       = "tab" + letra.Id;
            aTabItem.Header     = letra.Nombre;
            aTabItem.Content    = new TabLetraContent(letra.Letra, letra.Id, letra.Nombre);
            aTabItem.IsSelected = true;
            aTabItem.AllowDrop  = true;
            mainTabControl.Items.Insert(mainTabControl.Items.Count, aTabItem);
        }
        private void txt_buscar_KeyUp(object sender, KeyEventArgs e)
        {
            bool found  = false;
            var  border = (resultStack.Parent as ScrollViewer).Parent as Border;
            var  data   = new Datos.Da_letras().GetLetras();

            string query = (sender as TextBox).Text;

            if (query.Length == 0)
            {
                // Clear
                resultStack.Children.Clear();
                border.Visibility = Visibility.Collapsed;
            }
            else
            {
                border.Visibility = Visibility.Visible;
            }

            // Clear the list
            resultStack.Children.Clear();

            // Add the result
            foreach (var obj in data)
            {
                if (obj.Nombre.ToLower().Contains(query.ToLower()))
                {
                    // The wordcontains this... Autocomplete must work
                    addItem(obj.Nombre, obj.Id.ToString());
                    found = true;
                }
            }

            if (!found)
            {
                resultStack.Children.Add(new TextBlock()
                {
                    Text = "No se encontró ningun resultado."
                });
            }
        }