private void btxaddname_Click(object sender, RoutedEventArgs e)
        {
            //read details from screen
            string  firstName   = tbxfirstname.Text;
            string  lastName    = tbxlastname.Text;
            decimal hourlyrate  = Convert.ToDecimal(tbxhrinput.Text);
            double  hoursworked = Convert.ToDouble(tbxHWinput1.Text);

            //create employees object



            //add to  obervable collection

            //check which radio button is selected

            //if radiobutton full time then create full time employee
            if (rbfulltime.IsChecked == true)
            {
                //create a full time employee
                Employee e1 = new FullTimeEmployees(firstName, lastName, hourlyrate, hoursworked);
                salary = e1.CalculateMonthlyPay();
                employees.Add(e1);
            }
            //else if pt rb then create part time employee
            else if (rbparttime.IsChecked == true)
            {
                Employee e1 = new PartTimeEmployees(firstName, lastName, hourlyrate, hoursworked);
                salary = e1.CalculateMonthlyPay();
                employees.Add(e1);
            }
            //refresh display manually
            //lbxNames.ItemsSource = null;
            //lbxNames.ItemsSource = names;
        }
        private void Window_Loaded(object sender, RoutedEventArgs e)
        {
            //string [] names= {"jane","joe","jones","jess"};
            Employee e1 = new PartTimeEmployees("Jane", "Jones", Convert.ToDecimal(9.50), 10);
            Employee e2 = new  FullTimeEmployees("Joe", "Murphy", Convert.ToDecimal(10.50), 10);
            Employee e3 = new FullTimeEmployees("John", "Smith", Convert.ToDecimal(11.50), 10);
            Employee e4 = new PartTimeEmployees("Jess", "Walsh", Convert.ToDecimal(12.50), 10);

            employees.Add(e1);
            employees.Add(e2);
            employees.Add(e3);
            employees.Add(e4);

            lbxName.ItemsSource = employees;
        }