private void Button4_Click(object sender, EventArgs e)
        {
            var form1 = new Second_Main_Form();

            form1.Closed += (s, args) => this.Close();
            form1.Show();
            this.Hide();
        }
        private void PictureBox1_MouseClick(object sender, MouseEventArgs e)
        {
            var form1 = new Second_Main_Form();

            form1.Closed += (s, args) => this.Close();
            form1.Show();
            this.Hide();
        }