by reading argv[0] from the process group leader of the group that owns the tty
(tcgetpgrp()). This can't be done portably so some OS-dependent code is
introduced (ugh); OpenBSD, FreeBSD and Linux are supported at the moment.
A new window flag, automatic-rename, is available: if this is set to off, the
window name is not changed. Specifying a name with the new-window, new-session
or rename-window commands will automatically set this flag to off for the
window in question. To disable it entirely set the option to off globally (setw
-g automatic-rename off).