Mac OS X 10.4: Bug with display profiles and fast user switching also affects Intel-based MacBook

Posted by Pierre Igot in: Macintosh
July 26th, 2006 • 2:31 pm

With all the problems surrounding the purchase and subsequent return of our “mooing” black MacBook, I never got a chance to mention one bit of information that I was able to gather during the few days of regular use that we got out of the MacBook before returning it. And that bit of information regards the long-standing bug with display profiles and fast user switching.

As far as I can tell, this bug that was first introduced in beta versions of Mac OS X 10.4 back in the fall of 2004 (!) has yet to be acknowledged and fixed by Apple. (I can still reproduce it with Mac OS X 10.4.7 on my G5 Quad.) So it is interesting to note that this bug actually also affects Mac OS X 10.4 running on an Intel-based MacBook.

I was able to reproduce the bug on our MacBook within a couple of days of receiving the machine and setting it up. That’s how long it took me to partition the drive, reinstall the system from the DVD, configure my admin user environment, and install a variety of applications. After I’d done all this, I created a separate account for my wife, and turned Fast User Switching on in System Preferences.

I then switched to my wife’s account and tested a variety of things in that environment. Then, when I switched back to my own admin user account using Fast User Switching, bam! It happened again. The actual color shift was very noticeable, if somewhat different from the color shift on my G5 Quad when the bug hits. On the G5 Quad, all the colors become washed out, as if everything was too bright. On the MacBook, everything became blue-tinged.

The precious workaround with DMProxy worked on the MacBook as well, and enabled me to bring the colors back to normal in my admin user environment.

But I cannot help but note that, on this MacBook, I never used an external monitor attached to the laptop in a dual-monitor set-up and, more importantly, I never even created a customized display profile! This happened on a stand-alone MacBook running with no external monitor attached to it and using the default display profile included in System Preferences’s “Displays” preference pane. As well, when I set up the system on this MacBook, I didn’t transfer all my user preference files from another machine. I really did recreate most things from scratch.

For the longest time, I thought that this bug only affected people with a dual-monitor set-up or people using customized display profiles created using the Display Calibrator Assistant. But my experience with the MacBook clearly indicates that this is not the case, and that the bug can also affect users with a single monitor (the built-in screen of the laptop) and with the default display profile.

Now, I still don’t think that the bug will happen by default in Mac OS X 10.4 as soon as you turn Fast User Switching on and start using it to switch between user environments. If it did, then surely Apple would have noticed it by now, would have been able to reproduce it reliably, and would have fixed. As far as one can tell, in spite of numerous bug reports (from me and from others), they still aren’t able to reproduce it.

So, what causes it? At this point in time, the only possible cause that I can see is either a third-party software application or utility or a third-party piece of hardware. But which one? I have so many of them, and it’s absolutely impossible for me to install them one by one and test Fast User Switching between each and every installation. I just don’t have time for this!

I think it’s really time for Apple to start taking this bug seriously enough, and to do appropriate testing to try and reproduce the problem reliably. They can ask for my or someone else’s complete system profile, including all third-party applications and devices, and try to install these third-party applications and devices one by one and test FUS each time. Surely it must occur at some point because of the introduction of some specific third-party file/item. It seems to me that this kind of trouble-shooting is the job of a proper testing lab such as the one at Apple, and not of individual users at their own expense.

4 Responses to “Mac OS X 10.4: Bug with display profiles and fast user switching also affects Intel-based MacBook”

  1. Chris Grande says:

    I noticed this bug instantly when moving to 10.4, however I don’t use FUS. I noticed it in various pieces of software I use, NewsFire/Transmit/ the Finder! where UI controls were being processed with strange gamma shifts. This happened on my PowerBook and still occurs on my MacBook Pro, however it doesn’t occur when I connect my 20″ Cinema Display! Also if a launch an app, say NewFire that shows this bug with the external display connected then disconnect the display the color stays correct, if I re-launch the app the color is all screwed up. If I then reconnect the display the color gets even worse. I’ve filled detailed bug resports/regression test on clean 10.3 and 10.4 systems on various models… still nothing from Apple.

  2. Pierre Igot says:

    Not sure we’re talking about the same bug here… Mine is definitely related to FUS and only occurs when switching between user accounts. It also affects the entire screen and is not apparently related to a specific application.

  3. ssp says:

    I’ve seen the problem regularly when using my iBook G4 and FUS. No secondary screens there. And nothing but the standard colour profiles either.

    Haven’t really used FUS on the MacBook a lot yet, but I can’t see why that ‘feature’ shouldn’t have made it to the Intel builds as well.

  4. Chris Grande says:

    I figured that they are different issues, but it just shows the issues with ColorSync at the system level.

Leave a Reply

Comments are closed.