Is there any chance you can post this demo so that I for example can see how it has been set up?
Viewing post in MightyMouse + HoverDisplay Demo comments
There's a "Read Me" file with instructions included within the zip. To be honest, I'm working on a completely revamped version of this plugin, but it's far more ambitious code-wise so it's proving difficult to get just right. It'll still work the same for the most part, but it should be capable of processing more complicated text than the current version. For example, it should be able to handle embedded tags which it currently can't do.