private void etudiantsToolStripMenuItem_Click(object sender, EventArgs e)
        {
            Gestion_Etudiants gst_etd = new Gestion_Etudiants();

            gst_etd.MdiParent = this;
            gst_etd.Show();
        }
        private void Container_Load(object sender, EventArgs e)
        {
            Gestion_Etudiants gst_etd = new Gestion_Etudiants();

            gst_etd.MdiParent = this;
            gst_etd.Show();
        }