private void danhMụcHóaĐơnToolStripMenuItem1_Click(object sender, EventArgs e)
{
Form frm = new frmHoaDon();
frm.ShowDialog();
}
private void btnHoaDon_Click(object sender, EventArgs e)
{
frmHoaDon hd = new frmHoaDon();
hd.Show();
}
