private void btnRequest_Click(object sender, RoutedEventArgs e)
        {
            if (lbUsers.SelectedItems.Count == 1)
            {
                LoggedinUserClient liu = (LoggedinUserClient)lbUsers.SelectedItems[0];

                MainData.BmClient.GameRequestAsync(MainData.UserName, liu.Name);
            }
        }
        private void SelectMarkedUser(string user, List <LoggedinUserClient> ul)
        {
            if (ul == null || ul.Count == 0)
            {
                return;
            }

            LoggedinUserClient l = (from item in ul
                                    where item.Name == user
                                    select item).FirstOrDefault();

            lbUsers.SelectedItem = l;
            lbUsers.UpdateLayout();
        }