Mac OS Desktop coordinate problem I'm having a hard time working with Mac OS screen coordinates.  I can use ⌘+⇧+4 to get them, but each of my monitors does not have a unique coordinate system??!?

I have a desktop of 4 screens arranged in a 2x2 pattern. Each screen has a size of (2048 pixels x 1152 pixels).  (And the Apple Menu Bar is on the top-left screen).

⌘+⇧+4 gives the upper-left of each screen as (0,0) and the lower right as (2048,1152).

But each screen does that!

Technically, the coordinate system "should" run from (0,0) to (4096,2304). How do I differentiate the coordinates of the individual monitors?

Furthermore, when I create a window at (500,500) it creates it in the top-left monitor at (500,652)

So I just don't understand what's going on. How can I get an accurate coordinate map for the Mac OS desktop with multiple monitors?
If you have Developer Tools installed, you could try running Pixie.app and configuring that to give you coordinates. It might calculate them differently.