Topic: F2 - Customers; F4 - Items
the menu is not suppose to show when your press F2 and F4 from sales_order_entry.php
so customer.php replace line 22 with
page(_($help_context = "Customers"), @$_REQUEST['popup'], false, "", $js);
and items.php replace line 35 with
page($_SESSION['page_title'], @$_REQUEST['popup'], false, "", $js);