Se permiten números y carateres de control (si no se permiten los caracteres de control el borrar falla)
private void textAno_KeyPress(object sender, KeyPressEventArgs e) {
e.Handled = !(Char.IsNumber(e.KeyChar) || Char.IsControl(e.KeyChar));
}
private void textAno_KeyPress(object sender, KeyPressEventArgs e) {
e.Handled = !(Char.IsNumber(e.KeyChar) || Char.IsControl(e.KeyChar));
}