private void Button_Click(object sender, RoutedEventArgs e)
 {
     if (Name.Text != "")
     {
         DialogResult = true;
     }
     else
     {
         var da = new DoubleAnimation();
         da.From        = 1;
         da.To          = 0;
         da.Duration    = new TimeSpan(0, 0, 0, 0, 200);
         da.AutoReverse = true;
         Name.BeginAnimation(TextBox.OpacityProperty, da);
     }
 }