Bumping as I'm still in need of this. Name your price, I'd be happy to pay for this kind of plugin.
1. It can be useful as an alternative collision check without using or altering existing collision polygons.
2. It can be useful for picking intersecting BBoxes, and sorting Zorder.
3. It can be very useful for triggering a lot of other actions based on BBox overlap.
The reason I want this as a plugin/behaviour instead of doing it in events as I'm doing now, is mainly performance benefits.
As a behaviour placed on a certain sprite it could automatically pick any other sprites with BBoxes intersecting the sprite with this behaviour.
Maybe a modification to current LOS behaviour can be done to achieve this? Instead of using a radius, using sprites BBox?