private void btnAgregar_Click(object sender, EventArgs e)
        {
            frmAlumno alumno = new frmAlumno();

            alumno.ShowDialog();
            if (alumno.DialogResult == DialogResult.OK)
            {
                cat.Alumnos.Add(alumno.mialumno);
                listUpdater();
            }
        }
 private void btnModificar_Click(object sender, EventArgs e)
 {
     if (lboxAlumno.SelectedItem != null)
     {
         frmAlumno alumno = new frmAlumno(cat.Alumnos[lboxAlumno.SelectedIndex]);
         alumno.ShowDialog();
         if (alumno.DialogResult == DialogResult.OK)
         {
             cat.Alumnos[lboxAlumno.SelectedIndex] = alumno.mialumno;
             listUpdater();
         }
     }
 }