The coordinates assume that my screens are aligned at the bottom, which is not the case; they are aligned at the top, so screen 1 should be -1680, 0, 0, 1050. I suppose it wouldn't be a problem, except that my program interacts with AppleScript, which actually gets the proper coordinates. I can't just put a 150 pixel vertical offset (which is, of course, the difference in heights of the monitors), because I want to ultimately produce a real program. Am I missing something? Is there an alternative to NSScreen? I'm so close to finishing this project, but I can't make any sense out of this.