There are two ways to create menus: there's the easy way, and there's
the hard way. Both have their uses, but you can usually use an item
factory (the easy way). The "hard" way is to create all the menus using
Gtk::MenuShell calls directly. The easy way is to use Gtk::ItemFactory
which makes these calls for you. This is much simpler, but there are
advantages and disadvantages to each approach.
Item factories are much easier to use and to add new menus to, although
writing a few wrapper methods to create menus using the manual method
could go a long way towards usability.
