I read:
Also, it could be possible to lockpick the doors of houses. I think that people used to put Crystall Comm in their houses to know when someone was tresspassing the house. And, anyway, there can be secured items, but there is a limit... so thieves could steal items not secured.House owners can add 'friends' to the friends list of the house. All characters on the account of the house owner will be auto-friended to the house, except characters that are owners of another house.
All players who are not on the friends list of a player building will highlight grey to the owner and his friends if they enter that building. This allows the owner and friends to deal with trespassers without fear of getting flagged.