When I use and external monitor on a MacBook Pro 2014 model (HDMI), unlocking the laptop requires that I lift the lid to type the password in because it is the only screen out of the two that will ever show the desktop manager (login or wake screen). This goes for both Pantheon and after installing Xubuntu-desktop package to see if it would be different with LightDM; it's not.
Waking the laptop from sleep leaves both the laptop and external monitor blank, so a password cannot be entered; I've tried regardless to see if anything would happen; it doesn't do anything and I have to hold my power-button down to shut it off. I have tried both changing the primary displays and deactivating displays using Elementary OS's default stuff and using ARandR. Nothing seems to work.
I thought a lot of the early development for Elementary OS was done on a MacBook? It's why I chose Elementary. I've seen it on a lot of YouTube videos. Has no one tried an external monitor? A TV? I don't think the desktop managers (login screens) are using personal display settings and it is causing problems.
90% of the time HDMI works just fine, I'm just getting tired of not having suspend as a working option or having to lift the lid to unlock the screen saver and type in the password because the DM doesn't talk to any personal settings. An external Keyboard will talk to the MacBook, but doesn't actually do anything but wake it up to a blank screen I can't get past.
I have had both the default video drivers and have tried install NVIDIA stuff; it doesn't help.
Just someone please with Elementary on their MacBook try using an external monitor to at least see if it's just me or not.