R0J0hound ah that's a good idea. Not sure why I didn't think to use absolute to see if it moved and the regular X for position. For some reason I was thinking I needed to use one or the other.
That fixes the wake up problem. Although I still have the problem of when the mouse is awake and I slide to the next screen you see the mouse moving - which isn't a terrible thing, I just wanted it to stay in place and not "hover" over things as it moves across the screen.
In general if you set a sprite to mouse.x/y there is a tiny little lag - a player wouldn't notice, but because I swipe screens and move pretty fast with easing (meaning the screen swipe is not instant) you see the mouse move. So when I saw the absolute values, I was thinking those are the ones I want.
I tried viewport expression, but those seem to be pre-upscaling. I didn't see any 'screen' values in the Browser obj in c3 - maybe they removed that.
if I shut off Fullscreen mode in Properties the absolute value works perfect.