private void addCommentButton_Click(object sender, EventArgs e)
 {
     if (!string.IsNullOrEmpty(newCommentTextBox.Text))
     {
         Comment comment = new Comment()
         {
             Author = Program.AuthUser, EntityType = EntityType.Product, Text = newCommentTextBox.Text
         };
         _presenter.ProductComments.Add(comment);
         newCommentTextBox.Text = string.Empty;
         _presenter.Save();
     }
 }