private void btnNhomHang_Click(object sender, EventArgs e)
{
frmNhomHang NhomHang = new frmNhomHang();
NhomHang.ShowDialog();
KhoiTaoComboNhomHang();
}
public frmNhomHang showNhomHang()
{
frmNhomHang F = (frmNhomHang)getForm("frmNhomHang");
if (F == null)
{
F = new frmNhomHang();
F.Show();
}
F.MdiParent = this;
F.WindowState = FormWindowState.Maximized;
F.Activate();
return(F);
}