Mountain Lion bug fix: a Mission Control frustration resolved

Mission-Control-IconSummary of the fix: Trash the com.apple.dock.plist file in ~/Library/Preferences.

I recently upgraded to OS X Mountain Lion directly from Snow Leopard. Mostly I’ve been very happy with the upgrade. There are many new features I’m enjoying that I’ve not seen listed in reviews, such as improved Quick Look previews of Word docs, and doc previews directly from Spotlight results – all very helpful.

But one thing, a bug in Mission Control, has been driving me crazy.

I have long used Expose with hot corners (activated in System Preferences) to manage application swapping. I would mouse to screen top right, and see all my windows arranged for me to decide which app I wanted to switch into next, mouse to top left and see all windows for one particular app, etc.

But when I upgraded, Mission Control refused to work this way for me. Suppose I had several applications open. I would activate Mission Control – but see just one application window. Like this:

Mountain Lion Mission Control malfunction – only one app showing

Mountain Lion Mission Control malfunction – only one app showing

I searched the web high and low, and found a lot of people who are frustrated with Mission Control, though it’s not clear to me that their frustrations are the same as mine. I even posted a (quiet) rant on the Apple feedback page.

Eventually, I realised I could test whether the bug is in Mission Control itself, or in my Snow Leopard legacy preferences, by logging into a Guest account, and seeing how Mission Control worked there. And bingo – it behaved exactly as I thought it should behave. So then the challenge was to find where the screwiness was in my main user account preference settings, and use the age-old Mac trick for problems with any app – deleting the preferences file.

Doing this was momentarily complicated because I then found that Apple has concealed the user Library folder (which contains the Preferences folder) in Mountain Lion. However (Googling problem after problem), you can see it again by going to the Go menu in Finder, and holding down the Option key.

From there, I went into the Preferences folder, trying to find a file that I imagined might be called com.apple.missioncontrol.plist. But no such file exists. Eventually, I realised that the preference file I needed to trash is the Dock preferences: com.apple.dock.plist.

I dragged it to Trash, restarted, and voila! At last, Mission Control is working as it should do.

Mountain Lion Mission control working as it should, similar to the old Expose

Mountain Lion Mission control working as it should, similar to the old Expose

By the way, if you’re wondering why I have so few apps in my dock, it’s because I use Spotlight (command-spacebar, and start typing the app name) to launch applications. I keep the Dock on the left of my screen, and use dock hiding to keep my screen clean. I’ve always been baffled by Apple’s default Dock minefield of clutter at the bottom of the screen – nothing minimalist about it, especially if you’re using a small Macbook screen on which it takes up huge amounts of space! I keep the Mail app in the Dock though, because then I can still drag files and photos on to it as a quick and easy way of mailing them.

Though Macs are supposed to terribly intuitive to use, and that’s true up to a point, you’ll never get the most out of yours (or any other operating system) unless you fairly regularly Google ‘[Mac/your OS] hints and tips’, and teach yourself more about the hidden shortcuts and techniques that make life with any computer much less frustrating.

About David

I am an environmental writer, journalist and speaker living in Cape Town, South Africa.
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12 Responses to Mountain Lion bug fix: a Mission Control frustration resolved

  1. Becky says:

    Thanks for posting this! I’ve had the same issue and it’s really been interfering with my work efficiency. I’m still having a little trouble, though – I can’t seem to permanently delete com.apple.dock.plist. Every time I put it in the trash and then empty the trash it instantly appears back in my preferences folder. No amount of restarting seems to help. Any ideas? Sorry if I’m missing something obvious – I’m not the best with computers. Thanks!

  2. Nicolas B. says:

    Although you experience is interesting, the result is not what I call “working as it should do”.

    When you call Mission Control, you don’t see all your windows of all your apps. They are *stacked*. And that’s too bad.

    On my Snow Leopard, when I call Exposé, I see all my windows of all my apps.

  3. Karl says:

    This solution doesn’t work for me either. I am logged in as admin, I’ve deleted com.apple.dock.plist from terminal and restarted, but the Application Windows Hot Corner is still not working like it used to in Snow Leopard. Really annoying!!! I don’t even know what the use of this Hot Corner even is if you can’t see ALL of the Application Windows that are open. Maybe they’ve changed something in Mountain Lion since this post?

    • David says:

      Terribly sorry – I don’t know how to help you any further.

    • Nicolas B. says:

      I had the same problem as you. And now I have succeeded to make Exposé show all windows of all applications in Mavericks ! Unstacked. Like in Snow Leopard. Go to System Prefs → Mission Control. And untick “Group the windows by application”. Then press F9, and tadaa ! Exposé shows all the windows. Well, the windows seem to be organized by Space, but I don’t care, I always use one Space.

  4. Nicolas B. says:

    Do you know what the situation is in Mavericks ?

  5. Thomas says:

    Many thanks. It works for me !

  6. Thank You that did the trick! I wonder if I caused any harm in tossing out other preferences, such as:
    com.apple.dock.plist.yzDJNmT
    com.apple.finder.plist
    com.apple.finder.plist.4x9mPYI
    com.apple.symbolichotkeys.plist

  7. John says:

    Thank you for this post. It solved my Yosemite mysteries.

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