Q: Windows pile into one monitor after dual monitors sleep

I have 2 monitors (Dell 24" 4K) that have to be occasionally powered on and off to reactivate them after sleep (there is a long-running thread about this in this forum). This is in Yosemite, btw.

When I have my 2 monitors set up as separate spaces, the windows always pop back onto the correct monitor after power on/power off.

So, the scenario is:

I power down one of my monitors because it doesn't wake up.

All of the windows from this monitor will move to the active monitor.

I power the un-detected monitor back on.

All of the windows that were on this monitor leap back onto it and the montior wakes up.

The system always seems to remember which monitor the windows were on and does the correct thing.

If I do not have "monitors as separate spaces" on (checked), the windows would have to be moved by hand, back to the powered/on/off monitor.

I hope that's clear.

I checked my settings for Mission Control, and it was already set such that "Displays have separate spaces" was checked.  I did find that in the Energy Saver settings there is an option for turning off the monitor, which was set for 10min.  I have turned that off, but I have yet to test it as I have been busy with a new client all morning long.  I will definitely be able to test that change tonight.

After some experimentation, I believe I have confirmed that my issue is the display going into sleep mode.

Here are the steps I performed:

1. In Energy Saver I changed Display sleep to Never and used it for the day.  Even after sitting all night, windows are still where they should be when I start work in the morning.
2. Switched the Display sleep back to about 20min or so, and multiple times I came back to a desktop that was shoved to the upper left.

I hate to thing my only options are to either live with it or to completely shut off the display sleep and burn my fairly pricey monitor up quicker.  Maybe someone has another idea?

Any relief in the 10.10.4 update, issued recently?

I have it queued up in my updates, but I haven't had time to bounce yet.  I have been working non-stop on projects, which is why the moving windows are so annoying because I get off a call and all of my stuff is moved about.

This same problem in Yosemite 10.10.3 and 10.10.4 has been hindering my productivity for months. I am anxious to see it resolved. I have tried all the tips here. Nothing works. I have a Dell P2815Q 4K monitor and a Westinghouse LCM-22w3 monitor. My graphics card is an NVIDIA GeForce GTX 680 (which I firmware flashed to get EFI boot screen). With the NVIDIA Driver Manager, I have tried both the NVIDIA Web Driver and the OX X Default Graphics Driver. The annoying problem persists – Finder windows that I have placed on my right monitor get collected to the left monitor after 10 or more minutes of Display Sleep. Computer Sleep is set to never. Both monitors are set to 1680 x 1050.

Have you tried reversing which is the Primary monitor? ¿any change?

(use displays preferences Arrange pane to drag the MenuBar to the one designated "primary").

I'm having the same problem with a new Macbook Pro 13" running Yosemite. I have a Dell monitor at work and a BenQ monitor at home, both exhibit the same behavior in Yosemite only. My 2011 MBP running Mavericks does not have this issue with any monitor I've ever used with it.

My interim solution, until Apple decides to fix this issue, is to use SwitchResX by Stéphane Madrau – http://www.madrau.com/. I use "Save Desktop" and "Restore Desktop" from the SwitchResX menu in the menu bar. As long as the "piled up" windows are still open on the Desktop, "Restore Desktop" will put them back into place after wake from sleep. I have to manually select "Restore Desktop" – I wish it would restore the windows automatically. I talked to Stéphane about it and he said he can't do much better than this given Apple's current handling of sleeping monitors in Yosemite.

Is this issue still happening in El Capitan?

I too ran into this issue after purchasing two Dell p2415q 4k monitors for my late 2013 MBP running Yosemite 10.10.5.  My issue is resolved now.

After reading the thread, "eludwig" had a suggestion to check the box for "displays have separate spaces" in the mission control settings.  This enables each monitor to be "its own primary desktop" therefore having memory for window settings after waking from a long sleep.  I do have my energy settings set to "turn display off after 10min" with "prevent computer from sleeping automatically" "wake for wifi" and enable power nap" checked.

You can even test this by pressing the power button to turn one monitor off - where the windows will jump to the other monitor.  However, when you turn the monitor back on, they will jump right back into the remembered place.

This is happening to me too...main monitor is hdmi attached, and gets all the windows piled on it from the other, which is lightning-to-DP.  But! It doesn't always happen.

My system needs a password on wake, and I *think* I've detected a pattern where if the sleep is short, or if I wiggle the mouse and wait for the monitors to come back *before* putting the password in, things are fine.  Not positive, but it seems to be happening less lately, including overnite.

I can replicate this issue on my brand new MBP with Yosemite