private void dangNhapToolStripMenuItem_Click(object sender, EventArgs e)
        {
            frmLog _frmLog = new frmLog(this);

            _frmLog.MdiParent = this;
            _frmLog.Show();
        }
        public frmMain()
        {
            InitializeComponent();
            frmLog _frmLog = new frmLog(this);

            _frmLog.Show();
        }