Question about NSToolbar

[Germán Arias]

I'm just trying to use a toolbar, but the standard items
NSToolbarPrintItemIdentifier and  NSToolbarShowFontsItemIdentifier,
aren't active. I need do some special thing to active these items? Of
course, I can implement these, by hand, on the delegate method: 

- (NSToolbarItem*) toolbar: (NSToolbar*)toolbar itemForItemIdentifier:
(NSString*)itemIdentifier willBeInsertedIntoToolbar: (BOOL)flag

But I whant know how the standard items work.