void showAlertViewMenuItem_Click(object sender, System.EventArgs e)
 {
     if (alertDlg == null)
     {
         alertDlg = new AlertDlg();
         alertDlg.alertControl1.SelectedStockChanged += OnSelectedStockAndDurationChanged;
         alertDlg.Disposed += alertDlg_Disposed;
         alertDlg.Show();
     }
     else
     {
         alertDlg.Activate();
     }
 }
 void alertDlg_Disposed(object sender, EventArgs e)
 {
     alertDlg.alertControl1.SelectedStockChanged -= OnSelectedStockAndDurationChanged;
     this.alertDlg = null;
 }