I plan to get a 27" display to use with my iMac. I also would like to use it with my MBP from time to time. When I want to switch the display from the imac to the MBP do I need to shut down both computers hook up the ACD start the computer and then re set up in system preferences? or can I just switch on the fly and the computer will recognize the display and revert to the settings that I set up the first time i hook up the display?