Bizarre black outline on screen, seeing double

Take a look at Universal Access in the System Prefs. There may be some otions active in it.

Today, I had the same problem. You were right on track with Universal Access. I did the "remove and readd today changed plist files" routine, and com.apple.universalaccess.plist is the culprit. I could not see which option causes this thing, so I ditched the file and everything is fine again. I can reproduce the bahaviour by moving the "broken" plist into the Preferences folder again.

The strange thing is: I did not change anything in System Preferences today. Unfortunately, I also can't say what I did prior to this thing happening (did not pay attention to it at first).

Anyway: Here is what Property List Editor dumps out as the faulty plist, just in case someone is interested:


<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE plist PUBLIC "-//Apple Computer//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
<plist version="1.0">
<dict>
<key>PID</key>
<integer>1297</integer>
<key>closeViewDriver</key>
<true/>
<key>closeViewNearPoint</key>
<real>2</real>
<key>closeViewZoomFactor</key>
<real>1</real>
<key>com.apple.custommenu.apps</key>
<array/>
<key>contrast</key>
<real>0.0</real>
<key>mouseDriver</key>
<false/>
<key>slowKeyBeepOn</key>
<false/>
<key>voiceOverOnOffKey</key>
<true/>
</dict>
</plist>

The real answer is: turn off VoiceOver in Universal Access. You can also press Apple-f5, which will toggle VoiceOver on and off. VoiceOver creates a black square around selected icons.

Accidentally pressing Apple-f5 will turn VoiceOver on... :)