private void toolStripButton3_Click(object sender, EventArgs e)
        {
            GradeMainform frm = new GradeMainform();

            frm.ShowDialog();
        }
 public GradeAddModify(GradeMainform _frm)
 {
     InitializeComponent();
     cGrade    = new ClassGrade();
     this._frm = _frm;
 }