Mac OS X 10.4 (Tiger): Reliable fix for bug with calibrated display profiles and fast user switching

Posted by Pierre Igot in: Macintosh
January 10th, 2006 • 9:24 am

This bug with calibrated display profiles and fast user switching is a perfect illustration of Apple’s abject failure to respond to user feedback. As noted earlier, I reported this bug to Apple within the AppleSeed program more than a year ago, long before Tiger was officially released. I continued to report on this bug repeatedly even after Tiger’s official release, in the hope that it would be fixed quickly as part of the first couple of incremental system updates.

As far as I can tell, Apple never took my bug reports seriously. As of today, the bug is still not fixed. As recently as early December 2005, I was still communicating with them trying to make them see this bug. They were still claiming that they couldn’t reproduce it. I have sent detailed step-by-step procedures to reproduce it. I have sent screen shots illustrating the visual aspects of the bug that could be captured. (The calibrated profiles actually disappear from the list of profiles.) All to no avail.

As noted earlier, I am obviously not the only one affected by this bug. Not everyone is able to reproduce it, but it sure seems to be common enough. Other Betalogue readers are able to reproduce it, and there are reports about it on

I should also note that I tried to better circumscribe the bug when I moved from my G4 MDD to my G5 Quad. I tried to reproduce the problem with the plain vanilla OS installed on my brand new G5, with my two calibrated displays, and I couldn’t reproduce it. Then I restored a large number of settings (including several preference files) from my existing home folder on my G4 system, and, after that, the problem was back. So it must obviously be related to some system settings that do not exist in OS X by default but get added through user customization—although, based on the prevalence of the problem among Mac users, it can’t be a problem with a corrupted preference file. I reported this to Apple, and tried to get them to help me locate the possible culprits, but they never responded, which again demonstrates an utter lack of interest in solving this problem.

Apple needs to realize that, between a plain vanilla OS X install with no user customizations and a five-year old system install with tons of customizations and possible preference file corruption, there is a whole spectrum of real-life situations where people have an OS with a certain degree of user customization, all of which is supposed to be supported by Mac OS X. I am not talking about third-party system hacks here. I am simply talking about copying existing*.plist files from a previous OS install instead of having to painstakingly restore each and every user customization manually.

Besides, in this particular case, I am pretty much convinced that I would have recreated the problem even if I hadn’t restored*.plist files from a previous OS install. It would probably have started occurring at some point, after one additional user customization restored manually. The problem with this particular bug is that fast user switching is not something you do every five minutes. There was just no way that I could remember to test fast user switching again and again every time I made a change to my system preferences, just in case I had just made the system preference change that causes this bug to reappear. That’s precisely where I was hoping to get some guidance from Apple. I simply have no idea which system preference it is that causes the problem to reoccur. As far as I can tell, it could be anything. Only Apple engineers themselves know enough about the inner workings of Mac OS X to have a better idea of which system files/preference settings might be involved in triggering the reappearance of this bug. But based on my experience, Apple engineers can’t be bothered. Unless you present them with a perfect 100%-reproducible step-by-step process that triggers a bug, they won’t do anything. They won’t seriously try to reproduce the problem you are reporting on, no matter how serious the problem is and how sure you are, as an experienced Mac user, that it’s not a rare one-off thing.

On the one hand, I do understand that 100%-reproducible bugs get the highest priority (although in my experience even 100%-reproducible bugs can remained unaddressed for years, simply because Apple appears to have other priorities). On the other hand, here again, between 100%-reproducible bugs and one-off glitches that only occur once in a blue moon, there is a whole spectrum of bugs that occur often enough and are serious enough to warrant immediate attention. As far as I can tell, Apple’s current testing procedures are unable to cope with such a spectrum of issues.

Anyway, back to this particular bug with calibrated displays and fast user switching…

Until now, no one had been able to come up with a reliable and easy fix for the bug, short of actually restarting your Mac. Well, as far as I can tell, someone finally has. Check out this hint at Mac OS X Hints. When the bug occurs (i.e. after using fast user switching), you can actually bring things back to normal by executing a Unix program called DMProxy from within the Terminal application.

The Unix program is located here:

System › Library › Frameworks › ApplicationServices.framework › Versions › A › Frameworks › CoreGraphics.framework › Versions › A › Resources

It works! Just browse to this location and then take the DMProxy icon and drag it onto a Terminal window and press Return. This will insert the path to the program and then execute it. And your displays will go back to normal!

It is obviously shameful that Apple still hasn’t fixed the problem (i.e. tried hard enough to reproduce it in-house), but at least we now have a work-around which, as far as I can tell, works reliably and is fairly easy to use. (Just put an alias to the “Ressources” folder referred to above somewhere accessible and then it will just take a few steps.)

Congrats to the Mac OS X Hint contributor on finding this. And shame on Apple.

2 Responses to “Mac OS X 10.4 (Tiger): Reliable fix for bug with calibrated display profiles and fast user switching”

  1. ssp says:

    Hehe, I ran into the problem for the first time only a few weeks back and was so shocked I finally had to restart…

    Going from your reports I’m happy that this fixed was revealed so quickly after me reporting the problem. At least I can easily protect my eyes this way :)

  2. ssp says:

    P.S. You can even just double click the command line tool (or add its alias to the global script menu)

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