This has been previsouly reported. For More Information see: Reorder scripts in Manage Scripts via keyboard shortcut is broken in FMP11
This is one of many acknowledged bugs that can be found in the Known Bug List here in the Report an Issue section of the forum.
It can also be downloaded as a database file from: http://www.4shared.com/file/8orL8apk/FMP_Bugs.html
Thank you for your post.
The link provided by PhilModJunk is correct, as it was originally reported by you. This has been confirmed by our Testing department as a Cocoa issue, and it has been sent to Development for further review.