I use FLOW a lot, i prefer the option without using CTRL on the MX KEYS but then it's painful when I'm maximizing or trying to grab an app from the corner and then get automatically switched to the other computer, so then I go back to using CTRL but it doesn't works every time. My suggestion is that can there be a third option, to create a box, like a hot spot, that will allow you to pass the mouse from one computer to another, i.e. I will set my box (50px by 50px) to the far right of my monitor and only if i pass my mouse through it, it will appear on the other 50px by 50px box on the other computer, this way I can use FLOW w/o CTRL and still can manipulate application windows without having the trouble of switching (screenshot)