# Mac OS Desktop coordinate problem

I'm having a hard time working with Mac OS screen coordinates.

I can us cmd-shift-4 to get them, but each of my monitors does not have a unique coordinate system??!?

[Edit: Clarification]

I have a desktop of 4 screens arranged in a 2x2 pattern. Each screen has a size of (2048 pixels x 1152 pixels).

cmd-shift-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?

Thanks,

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By applying your elementary school math skills? -- Seriously though, if your screens have exotic relative positions, you can try to take a full screen shot and get the coordinates from the resulting picture. – Daniel Beck Dec 20 '10 at 14:17
I don't understand your question. You say that "each monitor goes from 0,0" but the implied "but not to…" is missing. What's "totalDesktopWidth"? Is that a variable is a program you're writing? As an aside: of course your screen isn't going to have a total width of 0… – msanford Dec 20 '10 at 16:16
@msanford, I've clarified my question. Sorry. – Stephen Furlani Dec 20 '10 at 16:37
@Daniel, I've clarified my question. – Stephen Furlani Dec 20 '10 at 16:38
You can try creating a screenshot area selection rectangle from the top left screen's top left edge to the opposite edge of the bottom right screen. It should give you the total width and height. If you want to access these properties programmatically, I suggest you post this question over on Stack Overflow. – Daniel Beck Dec 20 '10 at 16:48