private void button4_Click(object sender, EventArgs e)
{
frmQLNHOMHANG frm = new frmQLNHOMHANG();
frm.ShowDialog();
}
private void NhomHangToolStripMenuItem_Click(object sender, EventArgs e)
{
frmQLNHOMHANG frm = new frmQLNHOMHANG();
frm.ShowDialog();
}