private void ButInserirLi_Click(object sender, EventArgs e)
 {
     LimparControles();
     HabilitaControl(true);
     HabilitaBut(false);
     LbltituLi.Focus();
 }
 private void ButEditarLi_Click(object sender, EventArgs e)
 {
     HabilitaControl(true);
     HabilitaBut(false);
     LbltituLi.Focus();
 }