R – How to be notified of the Minimize button being pressed in an OSX Window

N.B.: this relates to private (SPI) functions of the CoreGraphicServices framework.

I am currently running a CGSConnection to the Windowserver as the UniversalController (with the Dock killed), and would like to know how I can be notified that a CGSWindow has had the yellow minimize blob clicked.

Is there a notification event that I can watch for with CGSRegisterConnectionNotifyProc?

Perhaps the answer lies in HIToolbox? Any experienced CGS hackers out there have an idea?

Thank you.