Question about stty -echo in cmdtool

[munnari!cluster.cs.su.oz.au!rex at uunet.uu.net]

Under suntools 3.4 and 3.5 the cmdtool appears to know when the pty it is
connected to has been stty'ed -echo. I believe that it does this by using
the TIOCTCNTL ioctl, but this is, in 3.[45], undocumented. If anyone has
information on how a program can be informed when this occurs I would be
thankful for the information. We are running 3.5 (Waiting for the source).

Thanks in Advance,
Rex di Bona,
rex at cluster.cs.su.oz.au
rex%cluster.cs.su.oz.au at uunet.uu.net
munnari!cluster.cs.su.oz.au!rex