Some programs don't support this xrandr feature very well. (The problem is that they show popup-menus on the wrong submonitor if they were opened _after_ splitting the screen). My workaround is to start all programs before splitting the screen, and all menus etc seem to work properly then.
https://gist.github.com/okke-formsma/60f3949492b51c48640884d...
https://imgur.com/a/etzCSlD
Some programs don't support this xrandr feature very well. (The problem is that they show popup-menus on the wrong submonitor if they were opened _after_ splitting the screen). My workaround is to start all programs before splitting the screen, and all menus etc seem to work properly then.