private void menuDangNhap_Click(object sender, EventArgs e)
        {
            FrmDangNhap frmDN = new FrmDangNhap();

            frmDN.ShowDialog();
            if (Islogin)
            {
                this.menuThongKe.Enabled       = true;
                this.menuHeThong.Enabled       = true;
                this.menuDangKi.Enabled        = true;
                this.menuDangNhap.Enabled      = true;
                this.menuTools.Enabled         = true;
                this.menuHoTroKH.Enabled       = true;
                this.menuQuanLy.Enabled        = true;
                this.menuThoat.Enabled         = true;
                this.menuQLKhachHang.Enabled   = true;
                this.menuQLNhanVien.Enabled    = true;
                this.menuQLChucVu.Enabled      = true;
                this.menuQLHoaDon.Enabled      = true;
                this.menuQLDichVu.Enabled      = true;
                this.menuQLPhongThue.Enabled   = true;
                this.menuQLLoaiPhong.Enabled   = true;
                this.menuThongTinPhong.Enabled = true;
                this.menuDatPhong.Enabled      = true;
                this.menuDatDV.Enabled         = true;
                this.menuTraPhong.Enabled      = true;
                this.menuTraCuuKH.Enabled      = true;
                this.menuTraCuuHD.Enabled      = true;
                this.menuTraCuuNV.Enabled      = true;
            }
            else
            {
                this.menuThongKe.Enabled       = true;
                this.menuHeThong.Enabled       = true;
                this.menuDangKi.Enabled        = false;
                this.menuDangNhap.Enabled      = false;
                this.menuTools.Enabled         = true;
                this.menuHoTroKH.Enabled       = true;
                this.menuQuanLy.Enabled        = true;
                this.menuThoat.Enabled         = true;
                this.menuQLKhachHang.Enabled   = true;
                this.menuQLNhanVien.Enabled    = false;
                this.menuQLChucVu.Enabled      = false;
                this.menuQLHoaDon.Enabled      = true;
                this.menuQLDichVu.Enabled      = false;
                this.menuQLPhongThue.Enabled   = true;
                this.menuQLLoaiPhong.Enabled   = false;
                this.menuThongTinPhong.Enabled = false;
                this.menuDatPhong.Enabled      = true;
                this.menuDatDV.Enabled         = true;
                this.menuTraPhong.Enabled      = true;
                this.menuTraCuuKH.Enabled      = true;
                this.menuTraCuuHD.Enabled      = true;
                this.menuTraCuuNV.Enabled      = true;
            }
        }