Black rectangle appears after Mac OS X 10.4.8 Update

This FAQ addresses an issue where a black rectangle appears and follows the mouse pointer after installing the Mac® OS X 10.4.8 Update.


After installing the Mac OS X 10.4.8 Update, a black rectangle appears on the desktop and follows the mouse pointer, as seen in the following screen shot:

The black rectangle is the preview rectangle for the Zoom feature of Universal Access preferences.


A bug in the Mac OS X 10.4.8 Update causes the preview rectangle to be visible, whether or not Zoom has been enabled in Universal Access preferences, if the following Zoom options are set:

  • Show preview rectangle when zoomed out is selected.
  • The Maximum Zoom slider is set to a Magnification value greater than 1, i.e. it is not set to the extreme left, indicating no magnification.

In prior versions of Mac OS X 10.4 Tiger®, Zoom must be On, in addition to the Zoom Options settings noted above, for the preview rectangle to be visible.


Perform the following steps in the order specified:

  1. Launch System Preferences.
  2. Select Universal Access.
  3. Select the Seeing tab.
  4. If Zoom is On, and you do not use the Zoom feature, select Off.
  5. Click Options....
  6. In the resulting sheet, if the option Show preview rectangle when zoomed out is not selected, select it. This is necessary if the preview rectangle is visible despite this option not being selected.
  7. Deselect Show preview rectangle when zoomed out. The preview rectangle should disappear.
  8. Quit (Command-Q) System Preferences.

A bug report has been filed with Apple on this issue. This FAQ will be updated as more information becomes available.

Did you find this FAQ helpful? You will find a wealth of additional advice for preventing or resolving Mac OS X problems in Dr. Smoke's book, Troubleshooting Mac® OS X.
Use of this site signifies your agreement to the terms of use.