Apartment
Currently one could give access to certain parts of a building by giving build trust. This was insecure and would often end up in issues with the landlord. It also reduced the whole building to be owned by the landlord whenever the build was saved.
The solution to this was to add an event which gives ownership to the specific user(s) that placed bricks on top of those bricks with the events specified. Due to this, this solution also works when reloading the bricks. At least for one of the guys owning it.