You seemed to have missed the question.
Why (or when) will mousecursors work with COCOA. These work fine with CARBON... and do nothing for COCOA (regardless or where in the program they are set)
Note : if I create a program with nothing more that ONE line of code to set cursor it works in Cocoa.... but in a larger app it does not (and there is only TWO lines to control the cursor)... One on MOUSEDOWN, and one on MOUSEUP
Also (from notes on the web)... changed to APP.MOUSECURSOR.... but it did not change until the MOUSEUP event... which makes it totally pointless
It's funny how I recently did something similar, but I was looking to set a Retina cursor. In my tests I did find that setting rectControl.mousecursor to a custom cursor worked (but didn't get the HIDPI version).
To get a Retina cursor, I loaded up a NSImage, then created a NSCursor from it. Then in the mouse enter event I make it the current cursor and in the mouse exit event, I made the standard pointer the current cursor.