I have discovered that this bug can be circumvented by using the following option in the "Device" section of the xorg.conf file:
Option "ExaNoComposite" "true" -- .''`. Stephen Powell : :' : `. `'` `- -- To UNSUBSCRIBE, email to [email protected] with a subject of "unsubscribe". Trouble? Contact [email protected] Archive: http://lists.debian.org/149147742.3758380.1382203607303.javamail.r...@md01.wow.synacor.com

