private void mornitoringFirstClick(object sender, RoutedEventArgs e)
 {
     if (monitoringFirstp == null)
     {
         MonitoringFirstPage p = new MonitoringFirstPage();
         monitoringFirstp = p;
     }
     content.Content = monitoringFirstp;
     CurrentControl  = content;
 }
        private void mornitoringFirstClick(object sender, RoutedEventArgs e)
        {
            MonitoringFirstPage p = new MonitoringFirstPage();

            content.Content = p;
        }