Hey Viktor,
So, I found some time to experiment with that. Here is the code after line 65
$options = $db->loadObjectList();
add the following code:
$application = JFactory::getApplication();
if(!$application->isAdmin()) {
foreach ($options as $key => $value) {
if($value->value == 1) {
unset($options[$key]);
}
}
}
where "1" is the category id. So if you have several categories to exclude you'll need to add more lines like
if($value->value == 2) {
unset($options[$key]);
}
you get the idea.
Regards,
Daniel