The Bug RF-371 (slider: the marker is outside the ruller if it is disabled) is marked as fixed. I have done some tests with RichFaces 3.1.0 RC1 and 3.1.0 Snapshot from 6th August on Tomcat 6.0.13. And the bug is still there.
In version 3.0.1 and 3.0.2 I had this problem just with Firefox. But now in version 3.1.0, I can reproduce this problem in Internet Explorer 6 and 7, too. Only in Opera my disabled slider will be drawn as expected. In Internet Explorer and Firefox 18.104.22.168 the marker is outside of the ruler.
Affected bug report: http://jira.jboss.com/jira/browse/RF-371
WAR Demo (with RichFaces 3.1.0 Snapshot from 6th August):