private void LevelGoBackBtn_Click(object sender, EventArgs e)
        {
            this.Hide();
            if (mmf == null)
            {
                mmf = new MainMenuForm();
                mmf.FormClosed += Mmf_FormClosed;
                mmf.Show();
            }

            else
            {
                mmf.Activate();
            }
        }
 private void Mmf_FormClosed(object sender, FormClosedEventArgs e)
 {
     mmf = null;
 }