private void bánHàngToolStripMenuItem_Click(object sender, EventArgs e) { if (Application.OpenForms["frm_hoadon"] == null) { frm_hoadon tthd = new frm_hoadon(); tthd.MdiParent = this; tthd.Show(); } else { Application.OpenForms["frm_hoadon"].Activate(); } }
public Lopdungchung(GUI.frm_hoadon f) { frmhd = f; }