private void btn_addPeriod_Click(object sender, EventArgs e) { //Add Period YearGroup selectedYear = (YearGroup)list_days.SelectedItem; if (selectedYear == null) { return; } if (selectedYear.Forms.Count() == 256) { MessageBox.Show("Operation not allowed, as you cannot have more than 256 forms per year."); return; } selectedYear.AddForm("Form"); ListViewItem lvi = new ListViewItem(selectedYear.GetBackForm().ToString()); //THIS IS INEFFICIENT, SO YOU SHOULD WRITE SOME MORE FUNCTIONS IN THE CLASS!!!!! list_periods.Items.Add(lvi); list_periods.Refresh(); }