private void buttonAdd_Click(object sender, EventArgs e) { DlgSessionVariable dlg = new DlgSessionVariable(); SessionVariableCollection ow = new SessionVariableCollection(_owner.Owner); for (int i = 0; i < listBox1.Items.Count; i++) { ow.Add(listBox1.Items[i] as SessionVariable); } dlg.LoadData(ow, null); if (dlg.ShowDialog(this) == System.Windows.Forms.DialogResult.OK) { listBox1.Items.Add(dlg.Return); } }