A CAPI interface.
The generic function
interface-extend-title is called by the system with an interface and its title before actually displaying the title on the screen. The result must be a string, which is actually displayed. There is no requirement for any relation between the title argument and the result.
The default method uses the values set by set-default-interface-prefix-suffix. You can specialize
interface-extend-title to get other effects.
CAPI User Guide and Reference Manual (Macintosh version) - 3 Aug 2017