I had the idea of making an addInteractive() function in World that would be essentially the same as addDecal, but would have event:Event as an additional parameter. It would add something to the stage that would do something other than just "be there". A ladder would be an example of what this function would create, but I don't want to change how the ladders are made. Other things this would create would be: switches, moving platforms, etc.
Would we be better off making functions for each thing that comes up (addSwitch, etc)? Also, does giving a variable of type Event include ALL AS3 events, or is Event an actual type of event?