ONNV terminal definitions are old and crufty
With a default install of snv_134 or oi_147, running something like vim inside screen produces very broken colours and what not.
I've attached an example screenshot someone has provided of an example issue. I believe their TERM is set to xterm-color, and they have exited vim from inside a screen. This combination is reportedly working fine in Linux.
I'm not a terminal emulation expert so I apologise for this problem description being a bit vague, but the default terminal definitions (termcap/terminfo?) break things like vim inside screen.
There seems to be a blog post about the issue by Lewellyn over here with a potential fix:
Although a simple and seemingly unimportant issue, I'd actually classify this as reasonably important as it is the simple annoyances that put off new users and converts from other UNIX platforms who expect this stuff to work out of the box.
Installing ncurses and setting "export TERMINFO=/usr/gnu/share/terminfo" works well as a workaround.