Related Items API
Related Items are part of the products delivered by GE like PNI, EO, etc.
For PNI, there is a call to mit!additional_related_items() on the RWO that is an iterator of related objects.
Map Tool Tips
4.3 introduced the hovering information functionality called Map Tool Tips… The map_tooltip_plugin functionality calls description() on the RWO that is being hovered.
The Thematics add-on1 allows you to change the styling of features based on various attributions instead of storing the fixed styles in the style database.