private void ShowCustomKCPTunForm()
 {
     if (customKcptunForm != null)
     {
         customKcptunForm.Activate();
     }
     else
     {
         customKcptunForm = new CustomKCPTunForm(controller);
         customKcptunForm.Show();
         customKcptunForm.FormClosed += OnCustomKCPTunFormClosed;
     }
 }
 private void OnCustomKCPTunFormClosed(object sender, FormClosedEventArgs e)
 {
     customKcptunForm = null;
 }