// Form1 form1;
        public Form1()
        {
            InitializeComponent();
            F_Login f_Login = new F_Login(this);

            f_Login.ShowDialog();
        }
        private void loToolStripMenuItem_Click(object sender, EventArgs e)
        {
            F_Login f_Login = new F_Login(this);

            f_Login.ShowDialog();
        }