private void pbx_HoaDon_Click(object sender, EventArgs e)
{
ThanhToanHD hd = new ThanhToanHD();
this.Hide();
hd.ShowDialog();
this.Show();
}
private void hoadonToolStripMenuItem_Click(object sender, EventArgs e)
{
pbx_HoaDon_Click(this, new EventArgs());
ThanhToanHD hd = new ThanhToanHD();
this.Hide();
hd.ShowDialog();
this.Show();
}