Creates a new #GMenuItem representing a submenu.
This is a convenience API around gio.menu_item.MenuItem.new_ and gio.menu_item.MenuItem.setSubmenu.
the section label, or null
a #GMenuModel with the items of the submenu
a new #GMenuItem
Creates a new #GMenuItem representing a submenu.
This is a convenience API around gio.menu_item.MenuItem.new_ and gio.menu_item.MenuItem.setSubmenu.