I've refactored the Grid format for Moodle 2.5 - available from https://moodle.org/plugins/pluginversion.php?id=3336.
The purpose of this release is primarily a clean up the code exercise facilitating more use of YUI, separation of the code from other plugins and removal of out of date web design practices - mainly the use of 'onclick' in 'a' tags. The shadebox code is now cleanly attributed to the format which means that you should be able to reuse / adapt it for your own purposes without conflicts.
The current version of 'code checker' has been applied as much as possible to bring the code in line with Moodle standards.
The change to YUI for link events has meant that the 'enter' key now removes the shadebox once shown.