Returns the array of identifier strings for the allowed toolbar items.
- macOS 10.10+
The toolbar making the request.
This method is called for tab view interfaces that use the
NSTab style. Use this method to specify all possible items that may be included in the toolbar. The order of the items in the array is used to set their position in the toolbar configuration palette. If you include custom identifiers in the returned array, you must also override the
toolbar(_: method to specify the content for those toolbar items.
If you override this method, you must call
super at some point in your implementation. The default implementation of this method returns the identifiers for all toolbar items that correspond to tabs in the tab bar interface.