Hello, I am going to get soon my late-2015 iMac 27" 5K. Currently I am using a MacBook Pro mid-2009. I would like to use my MacBook Pro as an external monitor for the iMac. Can it be done? If so, how? I have a female HDMI to Mini DisplayPort cable, and also a male HDMI to Mini DisplayPort cable. Can I use them to achieve my goal? Thanks guys.