convert bottom left orgin position to top left origin position (and the reverse)

I am wondering about the right way to开发者_高级运维 convert a bottom left orgin position to top left origin position (and the oposite operation) under Mac OS X taking into account: - Multi screen configurations - Where these screens can be arranged in all possible configurations.

Thanks in advance for your help,

Regards,

see How do I convert Cocoa co-ords from top left == origin to bottom left == origin

Good answers there...