Allow one flow machine to require ctrl to switch machines while the other does not.

Allow configuring which key to hold to enable switching from one machine to another (and make that configurable by machine).

A use case for both of these - I have a Macbook and a PC and switch between the two devices. I have the modifier keys switched on my mac so that keyboard shortcuts are easier to use across both machines. So, I have to press the cmd/alt key to switch from the Mac to the PC. When I switch machines in that direction, the PC acts funny for a second, I think because i was holding ALT for a minute as far as the PC is concerned.