save, apply, cancel - but what does apply versus save do?

I'm wondering about PRChangeCommand>>buttonSpecification ^ Array with: self saveButton with: self applyButton with: self cancelButton That puts save, apply, cancel on the design, edit, and settings panels. But I'm wondering why save, versus apply. What's the thought behind 'Apply" versus just having the save, cancel. -- = = = ======================================================================== John M. McIntosh <johnmci(a)smalltalkconsulting.com> Twitter: squeaker68882 Corporate Smalltalk Consulting Ltd. http://www.smalltalkconsulting.com = = = ========================================================================