About this Add-on
Hyperactive automatically scans your message before you sent it and make sure that all the links you've written are valid. If one of the hyperlinks isn't valid – you'll have a choice to make: confuse your recipient with an invalid link, or go back to the message and fix the URL.
Apart from being personally useful for me, I used this addon to learn the Bootstrap extensions system.
My conclusion and tip for addon developers would be to look inside the omni.jar in order to find the most suitable event(s) to observe.