private void thongKeDoanhThuToolStripMenuItem_Click(object sender, EventArgs e) { frmThongKeDoanhThu frm = frmThongKeDoanhThu.Instance; ShowTabages("Thống kê doanh thu", frm); SetSelectedTab("Thống kê doanh thu"); }
protected override void OnClosed(EventArgs e) { base.OnClosed(e); _instance = null; }