Conditional on H2344_BROKEN which can be disabled at the top of the file if
necessary. This appears to handle all the cases I was able to reproduce from
Pat's list, with the caveat that msg_window=f fails on very wide windows on
Mac OSX Lion with the default terminal emulation. When the emulation is set
to ANSI, it works (the failure mode is the output from a simple putchar() loop
across the contents of history called up from ^P wraps at about the middle
of the window).
92b15c5f8a