public void LoginButtonHandler()
 {
     IsRunning = true;
     SqlEESettings.LoginPossible = false;
     try { CT.LoginButtonHandler(); }
     catch (Exception e) { SIEEMessageBox.Show(e.Message, "Login error", MessageBoxImage.Error); }
     finally { IsRunning = false; }
     DataLoaded = true;
     SqlEESettings.LoginPossible = true;
     SelectedTab = 1;
 }