private void btnOK_Click(object sender, EventArgs e)
        {
            string role = WorkItem.State[Constants.CurrentRole] as String;

            if (!String.IsNullOrEmpty(role))
            {
                foreach (string user in SelectedUsers)
                {
                    if (!MembershipService.IsUserInRole(user, role))
                    {
                        MembershipService.AddUserToRole(user, role);
                    }
                }
            }
        }