private void START_Click(object sender, EventArgs e)
        {
            panel1.Visible = false;
            btnAbout.Visible = false;
            btnStart.Visible = false;
            this.BackgroundImage = null;
            //efmPanel1.Visible = false;

            efmPanel1.BorderStyle = BorderStyle.FixedSingle;
            s = new Snake (efmPanel1, glava1, tijelo1, glava2, tijelo2, hrana, Snake.Level.LevelExtreme);
            s.GameOver += s_GameOver;
            efmPanel1.Visible = true;
            efmPanel1.Focus ();
            efmPanel1.Refresh ();
        }
 void s_GameOver()
 {
     s = null;
     efmPanel1.Controls.Clear();
     START_Click(null, null);
 }