Thror's Key reads:

Response: After a location is added to the staging area, attach Thror's Key to that location. While attached to a location, Thror's Key gains: "Treat attached location's printed text box as blank, except for traits."

How about effects like this one, on Lone-Lands:

Forced: After placing 1 or more progress tokens on Lone-Lands, each player removes 1 resource token from one of his hero's resource pools, if able.
Response: After Lone-Lands leaves play as an explored location, Bilbo Baggins gains 1 resource.

The Forced text is clearly inactive while Thror's Key is attached. The Response, however, is triggered after Lone-Lands leaves play -- if it has left play, that means the Key is no longer attached, right?

Uf! Dificult question. I guess, yes Bilbo can get 1 resource, but if i thought "Bilbo must quit out 1 resource", then i would guess that Thror Key not triggers response, lol. So i don't know.

One question more: if you attach Thror Key to a location with "when revealed", does it trigger his "when revealed" or not?

You can find the same question about Warg's Lair here : http://community.fantasyflightgames.com/index.php?/topic/92338-unofficial-faq-compilation-of-answer-from-around-the-web/

The response would not proc. Thror's Key is a passive and would prevent the text to apply while the locaction leaves play even if it is also discarded as a result.

Thanks for that!

...and the "when revealed"? Thror' key cancel it?

No-- When Revealed effects resolve before the card is added to the staging area. Thror's Key can be triggered only after the card has been added to the staging area.

Ok, thanks