Apple has released an update for CarbonLib, the extension for Classic Mac OS that allows it work inside of Mac OS X. The update description is short and sweet:
CarbonLib 1.4 delivers improved functionality for Carbon-based applications on Mac OS 8.6, all Mac OS 9 releases and Mac OS X.
You may be able to find the update in the Software Update Control Panel in OS 9. You can also download the update directly from Apple, but you will be required to login with an AppleCare account. If you have trouble accessing that URL, go to Appleis Web site, click on "Support" in the navigation menu, click on "Downloads" in the sidebar of the Support page, and then look for the CarbonLib link in the list of updates on that page.