private void logInButton_Click(object sender, RoutedEventArgs e)
        {
            string userName = loginTextBox.Text;
            string password = passwdTextBox.Password.ToString();

            if (userName != "1" && password != "1")
            {
                if (userName != null && password != null)
                {
                    if (DatabaseHandler.LogIn(userName, password))
                    {
                        //UserScreen usrScreen = new UserScreen(userName);
                        UserScreen usrScreen = new UserScreen();
                        DataContext = usrScreen;
                        //Uri logPageUri = new Uri("/UserScreen.xaml", UriKind.Relative);
                        //Frame.Navigate(typeof(UserScreen));
                        NavigationService.Navigate(new Uri("/UserScreen.xaml", UriKind.Relative));
                    }
                    else
                    {
                        infoTextBlock.Foreground = new SolidColorBrush(Colors.Red);
                        infoTextBlock.Text       = "Wrong user name or password !";
                    }
                }
                else
                {
                    infoTextBlock.Text = "Insert user name and/or password";
                }
            }
            else
            {
                //UserScreen usrScreen = new UserScreen(userName);
                //UserScreen usrScreen = new UserScreen();
                //DataContext = usrScreen;
                //NavigationService.Navigate(new Uri("/UserScreen.xaml", UriKind.Relative));
                NavigationService.Navigate(new Uri("/UserScreen.xaml?par=" + userName, UriKind.Relative));
            }
            //ServiceReference1.Service1Client cln = new ServiceReference1.Service1Client();
            //cln.GetDataCompleted += Cln_GetDataCompleted;
            //cln.GetDataAsync(userName, password);
        }
        private void logInButton_Click(object sender, RoutedEventArgs e)
        {
            string userName = loginTextBox.Text;
            string password = passwdTextBox.Password.ToString();

            if (userName != "1" && password != "1")
            {
                if (userName != null && password != null)
                {
                    if (DatabaseHandler.LogIn(userName, password))
                    {
                        //UserScreen usrScreen = new UserScreen(userName);
                        UserScreen usrScreen = new UserScreen();
                        DataContext = usrScreen;
                        //Uri logPageUri = new Uri("/UserScreen.xaml", UriKind.Relative);
                        //Frame.Navigate(typeof(UserScreen));
                        NavigationService.Navigate(new Uri("/UserScreen.xaml", UriKind.Relative));
                    }
                    else
                    {
                        infoTextBlock.Foreground = new SolidColorBrush(Colors.Red);
                        infoTextBlock.Text = "Wrong user name or password !";
                    }
                }
                else
                    infoTextBlock.Text = "Insert user name and/or password";
            }
            else
            {
                //UserScreen usrScreen = new UserScreen(userName);
                //UserScreen usrScreen = new UserScreen();
                //DataContext = usrScreen;
                //NavigationService.Navigate(new Uri("/UserScreen.xaml", UriKind.Relative));
                NavigationService.Navigate(new Uri("/UserScreen.xaml?par=" + userName, UriKind.Relative));
            }
            //ServiceReference1.Service1Client cln = new ServiceReference1.Service1Client();
            //cln.GetDataCompleted += Cln_GetDataCompleted;
            //cln.GetDataAsync(userName, password);
        }