private void btnNav2_Click(object sender, EventArgs e) { BScha.MovePrevious(); }
private void btnNav4_Click(object sender, EventArgs e) { BScha.MoveLast(); }
private void btnNav1_Click(object sender, EventArgs e) { BScha.MoveFirst(); }
private void btnNav3_Click(object sender, EventArgs e) { BScha.MoveNext(); }