Test handling of empty menus.

Test handling of empty menus.

2003-09-30  Matthias Clasen  <maclas@gmx.de>

	* tests/merge-*.ui:
	* tests/testmerge.c: Test handling of empty menus.

	* gtk/gtkuimanager.c (_gtk_menu_is_empty): New function to determine
	whether a menu is empty. Used in gtkaction.c.
	(update_smart_separators): Also update the visibility of empty menus.
	(update_node): When creating a new menu proxy, insert an "Empty" menu
	item which only gets shown if the menu is empty.

	* gtk/gtkaction.c (gtk_action_class_init): Document the meaning of
	"is_important" for menu proxies.
	(_gtk_action_sync_menu_visible): New function to sync the visibility
	of menu proxies. Used in gtkuimanager.c.
	(gtk_action_sync_visible): New function to sync the visibility of
	proxies.