private void Window_Loaded(object sender, RoutedEventArgs e)
        {
            //Expenses ex1 = new Expenses("travel",30.99m, new DateTime(2019, 09, 10));
            //Expenses ex2 = new Expenses( "Entertainment",64.99m, new DateTime(2019, 01, 18));
            //Expenses ex3 = new Expenses("Office", 40.99m,new DateTime(2019, 11, 22));

            //List<Expenses> expenses = new List<Expenses>();
            expense = new ObservableCollection <Expenses>();
            expense.Add(Expenses.GerneratorRandomExpense());
            expense.Add(Expenses.GerneratorRandomExpense());
            expense.Add(Expenses.GerneratorRandomExpense());

            _txListExpenses.ItemsSource = expense;
        }
        private void txbtnAdd_Click(object sender, RoutedEventArgs e)
        {
            expense.Add(Expenses.GerneratorRandomExpense());

            txblkTotal.Text = Expenses.totalexpense.ToString();
        }