Wow! I didn't intend to spark this kind of debate, but I am pleased with the level of responsiveness on these boards.
What I am attempting to achieve: only show information sidebox to logged-in customers.
As it turns out it is somehow now working, and I have no idea what got it working. Perhaps it was just clearing cache or something stupid like that, but (to end the debate) all that needed to be overridden was the single file: includes/modules/sideboxes/information.php.
By the way, the tutorial in the FAQ which deals with sideboxes for logged in customers does not describe with any clarity how to do this for the information sidebox, which doesn't use any code resembling the sample code:
$show_featured= true;
What I did was replaced:
require($template->get_template_dir('tpl_information.php',DIR_WS_TEMPLATE, $current_page_base,'sideboxes'). '/tpl_information.php');
$title = BOX_HEADING_INFORMATION;
$title_link = false;
require($template->get_template_dir($column_box_default, DIR_WS_TEMPLATE, $current_page_base,'common') . '/' . $column_box_default);
with:
if (!$_SESSION['customer_id']) {
} else {
require($template->get_template_dir('tpl_information.php',DIR_WS_TEMPLATE, $current_page_base,'sideboxes'). '/tpl_information.php');
$title = BOX_HEADING_INFORMATION;
$title_link = false;
require($template->get_template_dir($column_box_default, DIR_WS_TEMPLATE, $current_page_base,'common') . '/' . $column_box_default);
}
I don't even pretend to know from PHP, so if this is a weak or potentially disastrous solution, please let me know the better way to do it. Either way, I think other users should have access to a fix for this