UsersBorrowed borCop;
        private void showUserToolStripMenuItem_Click(object sender, EventArgs e)
        {
            UsersBorrowed borCop = new UsersBorrowed(acessToDataLibrury.GetAllUsers());
            borCop.SelectUserName += new SelectItem(borCop_SelectUserName);
            if (borCop.ShowDialog() == DialogResult.OK)
            {
                acessToDataLibrury.ReturnBooks(borCop.returnedItem);
            }
            borCop.SelectUserName -= new SelectItem(borCop_SelectUserName);
        }

        void borCop_SelectUserName(object sender, EventArgs e)
        {
            borCop.AllBorrowedCopyByUser_dgv.DataSource =
                acessToDataLibrury.GetAllBorrowedCopiesByUser(new Guid(((ListBox)sender).SelectedValue.ToString()).ToString());
        }

public List<User> GetAllUsers()
      {
          List<User> users = new List<User>();
          DataRowCollection allUsers = libruryDataSet.users.Rows;

          foreach(institutelibraryDataSet.usersRow userRow in allUsers)
          {
              users.Add(new User(userRow.ID, userRow.Name, userRow.UserName, userRow.Password,Boolean.Parse(userRow.IsAdmin.ToString())));
          }
          return users;
      }

public partial class UsersBorrowed : Form
    {
        public event SelectItem SelectUserName;
        public DataGridView AllBorrowedCopyByUser_dgv
        {
          get { return allBorrowedCopyByUser_dgv; }
        }
        public List<string> returnedItem;
        public UsersBorrowed(List<User> users)
        {
            InitializeComponent();
            allUsers_ltbx.DataSource = users;
            returnedItem = new List<string>();
        }
}

public class User
    {
        public string Name { get; set; }
        public string UserName { get; set; }
        public bool IsAdmin { get; set; }
        public string ID { get; set; }
        public string Password { get; set; }
        public User(string id, string name, string userName, string password, bool isAdmin)
        {
            this.ID = id;
            this.Name = name;
            this.UserName = userName;
            this.Password = password;
            this.IsAdmin = isAdmin;
        }