Question changed due to new developments!
I was loooking for a way to hack the menu items in the custom menu page to add a "hide" checkbox and other options. The only way I found is to override the Walker_Nav_Menu class.
I think it's a quite tricky solution...
In the wp_nav_menu codex anyway i found many examples with filters and action to hack custom menus. Nevertheless I haven't found any documentation about these hacks.
Another idea I had is to treat menu items as custom post (they are actually), so i was wondering if the custom field api could be helpful for my purposes.
There is one big but simple feature that is missing from WP and I really can't understand why!!!
There isn't any way to just hide front end menu items without deleting them completely!
If for example I have a complex menu with many items and submenus and i want to hide it for a while, it's not possibile to do it! Just a checkbox with a display option would be enough.
It's me missing something?
If it's really missing, is there an API to modify the Appearance>menu section to add more capabilities?