private void btn_TraCuuSanPham_Click(object sender, EventArgs e)
 {
     TraCuuSanPham frmTraCuuSanPham = new TraCuuSanPham();
     frmTraCuuSanPham.Show();
 }
 private void TraCuuSsanPhamToolStripMenuItem_Click(object sender, EventArgs e)
 {
     TraCuuSanPham frmTraCuuSanPham = new TraCuuSanPham();
     frmTraCuuSanPham.Show();
 }