private void btnThanhToan_Click(object sender, EventArgs e) { if (ban.LayTrangThaiBan(idBan) == true) { frmThanhToanHoaDon frmHD = new frmThanhToanHoaDon(); frmHD.InHoaDon_Click += frmHD_InHoaDon_Click; frmHD.ShowDialog(); } }