private void btnLiberarOC_Click(object sender, EventArgs e)
 {
     FrmLiberarOC loc = new FrmLiberarOC();
     loc.MdiParent = this;
     OpenSubForm(loc);
 }
 private void ToolliberarOC_Click(object sender, EventArgs e)
 {
     FrmLiberarOC frm = new FrmLiberarOC();
     frm.MdiParent = this;
     OpenSubForm(frm);
 }