The idea is simple: Right-click with the item out to add events/toggle painting mode, and spray away. T The fillcan would effect every brick in contact with another that has the same color, and the paintcan would act like the default paintcan.
This would make eventing lava ridiculously easy, along with adding events to bricks in a localized area (perhaps showing you what you've done with an additional toggleable effect/color). A version that also names bricks would be helpful too.