void btn_Click(object sender, RoutedEventArgs e)
{
Button b = sender as Button;
Nhanvien nv = b.DataContext as Nhanvien;
ThemSuaNhanVien tsnv = new ThemSuaNhanVien(nv);
(this.Parent as StackPanel).Children.Add(tsnv);
}
private void btnThem_Click(object sender, RoutedEventArgs e)
{
ThemSuaNhanVien ts = new ThemSuaNhanVien();
(this.Parent as StackPanel).Children.Add(ts);
}