Hype Document Loader

↑ look at project
1.3 Tweaked notifyEvent to be additive, added hypeDocument.notifyEventAdditivum

This means you can register multiple callbacks and they receive the data in the sequential order you registered them and they can all manipulate the same event.data (additive).

Added bonus:
The notification system (since 1.2) is based on Hype's internal way of doing it and therefor this extension registers some needed helpers hypeDocument.notifyEvent and hypeDocument.notifyEventAdditivum (new). These can also be used by you to create your own events, making things possible discussed in this post and thread: