Here is an example of the code being used :
Here is the official page by the author:
I prefer mouseover rather than mouseclick after finding that several people didn't understand they needed to click to get the info whereas mouseover comes with the territory.
Hope this helps !
PS : for discussion's sake there is an issue with the fact that some browsers will display a value provide in title and this is sometimes displayed over the top of the box that is created by the above code.