/// <summary>
 /// Log in as one of the trainee in the list
 /// </summary>
 private void Student_list_view_MouseDoubleClick(object sender, MouseButtonEventArgs e)
 {
     try
     {
         BE.Trainee       trainee = Student_list_view.SelectedItem as BE.Trainee;
         MessageBoxResult result  = MessageBox.Show("האם ברצונך להתחבר למערכת בתור " + trainee.First_name + " " + trainee.Last_name + "?", "התחברות כתלמיד", MessageBoxButton.YesNo);
         if (result == MessageBoxResult.Yes)
         {
             StudentWindow studentWindow = new StudentWindow(trainee);
             this.Close();
             studentWindow.ShowDialog();
         }
     }
     catch (Exception) { }
 }
        private void LogInStudent(object sender, RoutedEventArgs e)
        {
            try
            {
                // search for trainee with the wanted id
                List <BE.Trainee> resualt = iBL_Imp.SearchTrainee(trainee_id.Text, true, false, false);

                // if there is no resualt
                if (resualt.Count == 0)
                {
                    student_error_message.Visibility = Visibility.Visible;
                    return;
                }

                // if the password is not correct
                if (resualt[0].Password != iBL_Imp.Encrypte(student_password.Password))
                {
                    student_error_message.Visibility = Visibility.Visible;
                    return;
                }

                ///////////////////////////////////////////////////////////
                student_error_message.Visibility = Visibility.Collapsed;
                student_password.Password        = "";
                trainee_id.Text = "";

                StudentWindow studentWindow = new StudentWindow(resualt[0]);
                this.Visibility = Visibility.Hidden;
                studentWindow.ShowDialog();
                this.Visibility = Visibility.Visible;
            }

            catch (Exception ex)
            {
                MessageBox.Show(ex.Message);
            }
        }