void xaphuongclick(object sender, RoutedEventArgs e)
 {
     frmxaphuong frmxaphuong = new frmxaphuong();           
     frmxaphuong.Show();
 }
 private void ChildWindow_Closed(object sender, EventArgs e)
 {
     frmxaphuong frm = new frmxaphuong();           
     frm.Show();
 }