I don't have easy access to a dual monitor mac without ordering some cables for my old mac laptop that I use for occasional testing so I'd really appreciate it if you could test this and let me know your findings.
Could you put your monitor setup in something like this:
with the primary monitor at 100% scaling and the secondary monitor to the right at a scaled resolution >100% (I don't know what the mac equivalent of this would be but I'm sure you know :))
As you move the mouse off the right of the main screen onto the right screen, does the MouseX value go up linearly or is there a jump back to a lower value as you cross the monitor edge like this?
Just a quick, yes it scales smoothly like the upper number in the gif or no it steps and drops back down like the lower number in the gif would be all the info I require, just make sure you have two different scales between the monitors. If you see a jump in the numbers could you add the setup res/scales you have?
Thanks in advance!