Mac OS X 10.3.8 (#8): PowerBook automatic screen brightness sensitivity; Safari world leaks

Mac OS X 10.3.8 (#8): PowerBook automatic screen brightness sensitivity; Safari world leaks

We continue our coverage of the recent Mac OS X 10.3.8 Update with more information about automatic PowerBook screen brightness and Safari "world leaks." (Note that we have moved coverage of "pop-up" blocking to a separate article, as the problem doesn't appear to be limited to 10.3.8.)

Excessive sensitivity in automatic screen brightness feature Yesterday we noted a reader report of apparent increased sensitivity in OS X's automatic screen brightness feature -- enabled via the "Automatically adjust brightness as ambient light changes" option in newer PowerBooks' Displays preferences -- since installing OS X 10.3.8. We've since received a significant number similar reports confirming this issue. Many readers report the issue is so bad that their screen "flickers." Mark Donohoe writes:

"I have noted this same problem on my 1.25GHz FW800 15" Powerbook. What was formerly a very useful facility which has been turned on since I bought the PowerBook a year and a half ago is now a liability. I had initially thought my backlight was malfunctioning, and was set for a return of the PowerBook for yet another screen repair (I had one replaced because of the dreaded white blotches). Then I recalled the [10.3.8 Update]. It is distracting and annoying. You can watch the problem in real time by opening the Displays in System Preferences, and if 'Automatically adjust brightness as ambient light changes' is checked, move your hands over the speakers and watch the [onscreen slider] jerk around while the screen changes. It is worst in late afternoon light where I work."

For some users, the screen's auto-brightness is so sensitive that very subtle changes in light are triggering the feature. For example, Eric Jasso writes, "The screen twitches as the shade from the tree near my window moves!" and Fred Brunner notes, "The screen dims almost instantaneously from something like someone leaning over your shoulder to look at the screen and blocking some ambient light." Phil Geller notes that simply moving his hands around the keyboard causes immediate changes in screen brightness; this wasn't the case before the update.

And although the initial reader report described this issue as occurring on one of the just-released PowerBook G4 models, a number of readers have experienced the same issue with older PowerBooks that provide this feature. Reader "Vincent" writes:

"It seems the ambient screen dimming issue reported on MacFixit is not limited to the newer PowerBooks. I own a first-generation [Aluminum PowerBook G4] (15", 1.25 GHz) that has become very sensitive to variations in ambient lighting since the upgrade to 10.3.8. With light coming in at an odd angle or while working under flickering fluorescent lighting, the screen brightness varies every second or so. Quite annoying...Resetting the NVRAM and/or PRAM didn't solve the problem (though I hoped it would)."

Many readers have become so frustrated by this issue that they've resorted to completely disabling the feature -- this "fixes" the problem, but then forces them to do without what had previously been a useful feature.

Safari world leaks Reader Mark Rougeux notes an increase in "world leak" errors in Safari since installing the update:

Since upgrading to 10.3.8, I am now getting messages of world leaks from Safari whenever I close all the windows. Used to get these a year or so ago, but haven't seen them in quite a while. The notice occurs constantly.

This is the first such report we've received; if you've experienced this issue, drop us an email at

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