//return document from hidden to visible
 private void button6_Click(object sender, EventArgs e)
 {
     if (Robots.showDocument(comboBox2.SelectedValue.ToString()))
     {
         MessageBox.Show($@"document change visibility succesfully.");
     }
     else
     {
         MessageBox.Show($@"document change visibility not succesfully!!");
     }
 }