private bool cbo_focus(ComboBox[] arrCbo)
 {
     if (arrCbo != null)
     {
         int countCbo = arrCbo.Count();
         for (int i = 0; i < countCbo; i++)
         {
             ComboBox cbo = arrCbo[i];
             if (cbo.Visible == true && cbo.Enabled)
             {
                 cbo.Focus();
                 return true;
             }
         }
     }
     return false;
 }