private void AcceptExecute()
        {
            try
            {
                userService.AcceptRequest(SelectedUser, User);
                string friend = SelectedUser.Username;

                using (SocialNetworkDbEntities context = new SocialNetworkDbEntities())
                {
                    tblUser userInDb = (from x in context.tblUsers
                                        where x.UserID == User.UserID
                                        select x).First();
                    UserList = userInDb.tblUsers.ToList();
                }
                Thread.Sleep(1000);
                string str = string.Format("You are now friend with {0} .", friend);
                MessageBox.Show(str);
            }
            catch (Exception ex)
            {
                MessageBox.Show(ex.ToString());
            }
        }