As stated in the Apple HIG[1] (via JMarc):
Ensure that a submenu’s title is undimmed even when all its commands
are unavailable. As with menu titles, it’s important for users to be
able to view a submenu’s contents, even if none of them are
available in the current context.
[1]
https://developer.apple.com/library/mac/documentation/UserExperience/Conceptual/AppleHIGuidelines/Menus/Menus.html#//apple_ref/doc/uid/TP30000356-TP6
// Only these kind of items affect the status of the submenu
if ((cit->kind() == MenuItem::Command
|| cit->kind() == MenuItem::Submenu
- || cit->kind() == MenuItem::Help)
- && cit->status().enabled()) {
+ || cit->kind() == MenuItem::Help)) {
enabled = true;
break;
}