Multiple Displays have problems with El Capitan

Except with a ASUS MM169+ external usb screen you can't switch it on, because the 'displays have separate spaces' causes mission control to crash when using two monitors. I also have a 23 inch Samsung PC pmonito with hdmi display which my Mac Mini htinks is a TV, and which when using airplay, goes totally mental with the mirroring/extend options, and messes up the screen resolutions on all monitors. El Capitan is truly a Mess. And i am not upgrading to Sierra, because i don't like the new features at all, and Siri is not an option on my Mac Mini which has no microphone. I did install Sierra once and formatted it after 2 days in disgust and reverted to El Capitan, despite all its bugs, such as this one with multiple screens. app Window focus is also all over the place when using multiple screens, with apps appearing offscreen with just a corner visible. Watching video likes to make one screen go black while the other plays. With Mavericks everything used to work so well. Since then, Yosemite, Capitan, Sierra.. all inferior to Mavericks

By the way APPLE.. your new forum announcement message has a bad script in it, addressing us uisers as 'APPLE ID!' instead of our name

The script is supposed to print the name of user, but it doesnt.. see below screenshot; is says 'Apple Id' instead of username. Or is that the name of a forum?

Thailand Amulets wrote:

By the way APPLE.. your new forum announcement message has a bad script in it, addressing us uisers as 'APPLE ID!' instead of our name

The script is supposed to print the name of user, but it doesnt.. see below screenshot; is says 'Apple Id' instead of username. Or is that the name of a forum?

No, that is not a mistake. It's an announcement about the new Apple ID forum. I understand English is not your native language and you have some difficulty with it. However, had you clicked on the link, it would have been clear.

the displays have separate spaces is one problem. that setting solves some but not all issues

i have a square 19 inch dell 1080p screen and a 23 inch wide 16:9 display wityh hdmi connector

if i use itunes and try to play a movie one screen goes black (either depending on which screen i have itunes in)

if i try to fullscreen in vlc or itunes, one screen goes black

if i try to use my asus mb169+ usb display, and watch fullscreen video, one screen goes black (either depending on which screen im watching on)

I have 2 screens so i can watch video in fullscreen on one and work on the other

However, it is not possible due to the issue you mention here, and the ones i mention.

Also creates problems with window position when i open an app, the apps appear halfway outside of the right of my display with only one part of the window visible. deleted all prefs files and plists to no avail

If you turn off the "Displays Have Separate Spaces", you get the issue you describe.

Playing something in full screen makes the second screen black.

The usual option is to to have this setting ON. It is now clear after such a long thread which problem is whose, and who has this on or off.

I recommend it to be ON at all times.

I have a similar issue. I have a Macbook Pro Retina and two external Dell monitors.

Everything worked fine before I unplugged my two external monitors yesterday to leave work and plugged them in again this morning.

At first, monitor two didn't come/turn on, so I tried switching ports – and now none of my two external Dell monitors will come/turn on.

I had the Macbook set up with a Mail/calendar split view – and monitor three setup with two Terminal windows split view.

I will try the SMC reset procedure – but this is obviously not a sustainable solution, for someone who plugs/unplugs several times a day to go to meetings etc.

MacBook Pro (Retina, 15-inch, Early 2013)

Does "Detect Displays" help in this case?

You get that by opening the displays preference, and holding down the option key:

In my case, the Menu Bar and the Dock no longer show on my second display.

Ahh – never caught that, that "Detect Displays" is now hidden that way.

In this mornings variant of the issue, "Detect Displays" actually helped – so thank you very much!

I went through the SMC Reset Procedure, and it did not help. I still have no Menu and no Dock on the second display.

That is interesting that you have to use the Option key. Why did they not just make another button? And how did you know that you had to use the Option key? Anyway, I tried it, and I still do not get the Menu or Dock on the second display.

Same issue on MacBookPro with an upgrade to El Capitan. Things worked fine initially with two external monitors at work. Went home and plugged in two different monitors. That worked fine. Issues appeared after returning to work and plugging in the original two monitors:

1. the dock and menu only one one monitor

2. graphics issues (slow performance, application windows flickering)

From this point onwards the system only works ok without external monitors, or with only one external monitor but only with mirroring.

there are a handful of posts on this forum and others where dual monitor mac users are having some form of an issue with their setups. Some owners of older Mac Pro's have said they're rebooting sporadically. I have not tested it out at this time so that's all the info I found at this time.

Rdruhl wrote:

That is interesting that you have to use the Option key. Why did they not just make another button? And how did you know that you had to use the Option key? Anyway, I tried it, and I still do not get the Menu or Dock on the second display.

Try System Preferences->Mission Control

It appears that the setting for "Displays have separate Spaces" was lost. You need to have that box CHECKED in order to have menu bars (and the dock, if it is set to appear at the bottom) on every display.

You need to log out and log back in for this change to take effect.

Thanks, Luis, that did the trick! I am a happy man again! 😎