private void button3_Click(object sender, EventArgs e)
 {
     ll();
     Backup_panel.Show();
     backup backup = new backup();
     panel4.Controls.Add(backup);
 }
 private void ll()
 {
     panel4.Controls.Clear();
     employee_panel.Hide();
     product_panel.Hide();
     supplier_panel.Hide();
     home_panel.Hide();
     setting_panel.Hide();
     report_panel.Hide();
     costumer_panel.Hide();
     Backup_panel.Hide();
 }