Its become more common in recent years, It`s celebrated the same way as in the US with trick or treat or whatever its called.
But most people don`t celebrate it.
I can imagine lots of Norwegian witch and gnome costumes
a wise man once said "If someone doesn't want responses to his/her posts, then s/he shouldn't post them. If someone wants specific users to not respond...well, that's too bad." (link)
