Hello. I am confused about 4k based on a few things I have read. I am either buying a new Macbook Air or a pro in the next few days. I plan to use with an external 4k monitor for a few hours day. So can the Macbook air be used with a monitor 4k at @60hz? I plan to use this with a Dell P2715Q 4k. https://support.apple.com/en-us/HT202856 I see Macbook Air 2015 listed. I also read this http://forums.macrumors.com/showthread.php?t=1855880 I think this is just using macbook Air screen. Thanks if you can help answer this for me.