I don't know what they are exactly called but what I mean is
1) Defeating a boss and returning to the boss select screen will make that boss button darker/locked (you can still enter in it but when you get to the boss room you just end the mission, like in the megaman games)
2) Defeating a boss and returning to the same room (different then above) in a one-big-level game will not re-trigger the same boss fight (metroid-esque games and maybe RPG games as well)
3) the boss cannot be fought at the moment (altough you can enter it's room, the boss may be not in the room or it's static like it's egg is not hatched) and you have to visit the room later before you fight it (you know, get an item or something before you can trigger it)
Are these possible on Construct and if so what should I search for to get/find/read the tutorials or examples about advanced use triggers/variables.