may be a carry over from an older version. In a file that was started on the first version of 0.7 (i think), one trash container (the green ones) that i was using to store trash, kerfur parts and kerfur itself became entangled with the mail box. This wouldn't be a problem if it wasn't for the fact that it seems like creating a new save file (or simply leaving that save?) obliterates everything on that trash container (and also the mailbox) now.