How do I make this particular trigger?

[Roarex]

Being relatively new in the world of mapmaking, I really need help for just this thing. I intend to do something like :

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How do I close this thread? I found out how to do it already =))

 

[tobbygnome]

You know its actually a good idea to leave your questions on here, because even if you found a way, someone on here could have found a more efficient way and teach you some things.

Also people who might have the same question or problem as you could find the solution in here.