I have just got a 4k monitor to use with my MacBook and it’s awesome. I use it with my MacBook closed so just a primary screen. I also have an Apple magic keyboard and mouse. Couple of things that bug me, when I’m using my MacBook and then plug in the monitor the windows stay small and the desktop gets bigger due to the resolution change. Also can you store a 4k wallpaper that is used automatically when I plug in the monitor and goes back to the MacBook resolution when unplugged? First world problems but are there any utilities to help with these?