A GTK.MenuShell is the abstract base class used to derive the
W(Menu) and W(MenuBar) subclasses.
A GTK.MenuShell is a container of W(MenuItem) objects arranged in a
list which can be navigated, selected, and activated by the user to
perform application functions. A W(MenuItem) can have a submenu
associated with it, allowing for nested hierarchical menus.
Signals:
activate_current
An action signal that activates the current menu item within the
menu shell.
cancel
An action signal which cancels the selection within the menu
shell. Causes the selection_done signal to be emitted.
deactivate
This signal is emitted when a menu shell is deactivated.
move_current
An action signal which moves the current menu item in the direction
specified by the third argument.
selection_done
This signal is emitted when a selection has been completed within a
menu shell.
GTK.MenuItem()->set_submenu()