private void btnAddOne_Click(object sender, EventArgs e) { if (cmbActive.Text == "Register" && mainRegister != null) { mainRegister.Add(); GlobalMethods.AddMessageToTextbox(mainRegister.GetLastMessage(), txtMessages); } else if (cmbActive.Text == "Diagnose" && mainDiagnose != null) { mainDiagnose.Add(); GlobalMethods.AddMessageToTextbox(mainDiagnose.GetLastMessage(), txtMessages); } }