protected void AddTask_Click(object sender, EventArgs e)
        {
            var taskName    = NewTaskName.Text;
            var categoryIds = NewTaskCategories.Items.OfType <ListItem>()
                              .Where(i => i.Selected)
                              .Select(i => int.Parse(i.Value))
                              .ToList();

            new TasksService().AddTask(taskName, categoryIds);

            NewTaskName.Text = string.Empty;
            NewTaskCategories.ClearSelection();

            LoadTasks();
        }
 private void LoadCategories()
 {
     NewTaskCategories.DataSource = new CategoriesService().GetCategories();
     NewTaskCategories.DataBind();
 }