I've had this same Spotlight results scroll focus change OS bug ever since Mountain Lion. I've observed it on 3 different macbook pros, both with an upgrade to Mountain Lion from Lion, and also a complete CLEAN install of Mountain Lion on a brand new disk where I've not dragged over any system files, preferences or apps. For me, all ML exhibit this bug from 10.8 to the most current 10.8.3.
I have not edited the Search Results categories that are selected (in Preferences > Spotlight)
The only time this has not occurred is in the first 2 days of the using the clean install of ML. The scroll focus behaved correctly even with a lot of results. It's now been a week since the clean install and the scroll focus change bug is now active again since day 3. It is possible to scroll slowly with the mouse wheel/gesture and it won't always (10% of the time?) snap focus to the top.
Thanks for the reference link above, but it was not helpful to me:
https://discussions.apple.com/thread/2577564?answerId=12261261022#12261261022
- The thread refers to OS 10.6., and I did not observe this bug in that OS, or 10.7.
- One recommendations is to delete the plist (preferences), but this is not a practical solution because the problem comes back quickly.
- The other recommendation is to turn off calculate size of files or the Spotlight results folder. It is not possible, as far as I can see, to turn calculate sizes on in the View Options for the Spotlight results window. It is possible to turn on/off sizes as a column in the results, but this made no difference with the bug.
Other tests I've performed that did not fix the bug:
- Change "Show scroll bars:" to "Always". This made no difference.
- Change "Click in the scroll bar to:" to "Jump to the spot that's clicked". No difference.
Other tests that could be performed:
1) System Preferences > Spotlight: Search Results - turn categories on and off to see if that makes a difference.
And finally, this has reduced the problem to occurring only 10% of the time now!
turn off Smooth Scrolling. This is no longer a checkbox in System Preferences > Appearance in 10.8 ML, so you have to use a shell command in Terminal. If you want to explore this approach look at these two references:
http://hints.macworld.com/article.php?story=20120726122633912
http://www.marekbell.com/how-to-disable-smooth-scrolling-in-mountain-lion/
Now I'm waiting to see if other parts of the ML OS will be negatively affected by turning off Smooth Scrolling, and then I'll decide which is worse. Bottom line, this is not a fix, but it seems to have reduced the occurrence of the Spotlight results scroll focus change OS bug.