Ram-Ashwin@cs.yale.edu (Ashwin Ram) (02/17/89)
[We do not get gnu.emacs.bug, so I'm posting this to comp.emacs. Please
forward this to the appropriate person. Sorry for the inconvenience.]
GNU Emacs 18.52.26 of Wed Feb 15 1989 on leo.ring.cs.yale.edu (Domain/OS)
We recently switched over from 18.48 to 18.52. Last night, while logged in
on a vt200 terminal over a slow phone line, I noticed a couple of problems:
1. When inserting characters in a line, 18.52 was redrawing the rest of the
line (to the right of the characters I typed) instead of just pushing it
to the right (as 18.48 used to do).
2. Scrolling sometimes left behind a line (or part of a line) from the
previous screen.
3. The mode line got messed up once during a display-time update. I could
not recreate this.
I have never encountered these problems in 18.48 with the same terminal and
termcap file.
To test this further, I ran 18.48 and 18.52 in turn with TERM = vt200, using
the same /etc/termcap file, typed in a test line, and started a termscript.
I then hit spaces at the beginning of the test line. Under 18.48, the test
line was pushed smoothly to the right, but under 18.52 the line was redrawn
on each keystroke.
I then looked at the termscript. They appeared as follows (the first line is
the actual termscript, with the ESC character replaced by ^[ for readability.
the second line is a description of what the characters are, where "*" marks
the SPC that I typed. The test line is (open-termscript "~/52") in the
second case):
18.48 termscript
----------------
^[[4h ^[[4l^[[4h ^[[4l^[[4h ^[[4l
im * ei im * ei im * ei
18.52 termscript
----------------
(open-termscript "~/52")
* ^M nd * address
It looks like 18.48 is using "im" (insert mode) and "ei" (end insert) to
insert the SPC, but 18.52 is using "nd" (non-destructive space) and some sort
of cursor addressing, along with complete rewriting of the test line.
Since I'm using the same termcap (which specifies "im" and "ei" for this
terminal), and since 18.48 works correctly, I conclude that this is a bug in
18.52.
A fix would be appreciated. Thanks.
-- Ashwin.
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