How Is the "Main Screen" defined?

I’ve just transferred to a new MBPro, and one of my macros doesn’t perform the way it did on the previous one.

Both MacBooks are / were attached to an external screen, the macro is written to execute relative to the main screen (rather than the front window).

The macro now executes on the MB Pro screen only, even when initiated from an app window being used on the external screen.

I can’t find a definition of “main screen” on the wiki or in the user manual - is it the primary screen (i.e. not external), or the one currently being used?

Also, is there any reason why this behaviour would change after transferring the library from one machine to another?

The Main Screen is the monitor with the menu bar on it, which was a lot clearer when only one monitor had a menu bar.

Now it is the monitor with the tiny fake menu bar on it in the System Preferences, Displays, Arrangement panel.

The top left corner of the Main Screen also represents the origin of the desktop (ie, 0,0 on the entire desktop is the top left corner of the Main Screen, other coordinates are relative to that).

Peter, thanks for your prompt reply.

I’ve switched the main screen in the preferences panel, and the macro works just as it did previously.

I don’t recall changing the main screen on the old macbook pro, clearly it was also set to the external monitor.

Thanks again,