private void ProovedoresToolStripMenuItem_Click(object sender, EventArgs e)
 {
     WindowsFormsApp1.SupplierForm supplierForm = new WindowsFormsApp1.SupplierForm();
     supplierForm.SetParent(this);
     supplierForm.MdiParent = this;
     supplierForm.Show();
 }
 public void SetParent(SupplierForm form)
 {
     refParent = form;
 }