Mac OS X 10.1.5: Video Mirroring Setting Changes After Upgrading

Symptom

After updating to Mac OS X on a computer with an additional display connected, extended desktop is enabled instead of video mirroring.


Solution

Use the Displays preference pane to re-enable mirroring:

1. Open System Preferences from the Apple menu.
2. Choose Displays from the View menu.
3. Click the Arrange tab.
4. Select Mirror Displays.
5. Quit System Preferences.