Thanks for the answers.
But this is kind of confusing! Hmm, it seems the activity doesn't need to influence the present time in anyway. You could say it has to be connected with it one way or another, but "one way or another" is too generic...
I checked my other threads about the present perfect continuous, and they are incomplete, so maybe that's why I still don't understand. It's going to be a mess... maybe I'll post something else later.
Anyway, it seems everyone agrees on the fact that the present perfect continuous implies that the action is still ongoing or the whole situation has not come to an end. Unless it's clear from the context, and there's a strong connection with "now" (usually a "result"). But it seems you accepted that example about the search on the net, and there's no connection with the present, is there?
See you later, maybe