private void NavigateToViewMethod(string destination)
        {
            try
            {
                if (Destination != destination)
                {
                    Destination = destination;
                    switch (destination)
                    {
                    case "BillDisplay":
                        CurrentViewModel = new BillDisplayViewModel();
                        break;

                    //case "Categories":
                    //    CurrentViewModel = new BillsCategoriesViewModel();
                    //    break;
                    default:
                        break;
                    }
                }
            }
            catch (Exception ex)
            {
                MessageBox.Show(ex.ToString());
            }
        }
 public BillViewModel()
 {
     Destination       = "BillDisplay";
     _currentViewModel = new BillDisplayViewModel();
 }