private void addIntermediateStructure_Click(object sender, EventArgs e) { var dlg = new FormInsertIntermediateStructure(this.currentFile); if (dlg.ShowDialog() == System.Windows.Forms.DialogResult.OK) { IntermediateStructure field = dlg.Result; this.lstStructure.Items.Add(field); this.currentFile.StrutureList.Add(field); } }