bug in emacs 21.2.1?

bug in emacs 21.2.1?

[kim.knowles]

I am running RedHat Linux 7.2, and Emacs version:
GNU Emacs 21.2.1 (i686-pc-linux-gnu, X toolkit, Xaw3d scroll bars) of 2002-05-03

I have been using emacs since 1992 (primarily using Emacs 19) and
updated recently to Emacs 21.  It is very impressively good and I have
been enjoying many aspects of it.  However, today I discovered a
disturbing behavior that I think must be a bug.

I like to use Emacs fully maximized vertically, but with the default
80-char width, and often I divide it vertically into 2 parts (C-x 2)
and switch between them.  On occasion, these two buffers really are
navigating two different points in the same file.

When I search for an item, when I find the line I want I often hit C-l
to redraw the buffer with that line centered vertically.  I believe
that is what it does.  However, the disturbing behavior is that when I
have found the spot in the top buffer, when I go to the the bottom
buffer and find the spot I want there, when I hit C-l, the other
buffer also moves.  It moves by what appears to be the same amount I
moved my cursor in the lower buffer from the time I switched to that
buffer until the C-l.

Quick recap:

Open file foo.txt (which is ~1800 lines long).  
C-x 2.
In top buffer, search for pattern XYZ.
C-l.
Switch to bottom buffer (C-x o).
Search for pattern ABC.
C-l.

The top buffer is no longer at XYZ, it is some arbitrary jump away from
where it used to be.

This behavior is very frustrating, and I cannot think of any instance
where it would be desirable. 

My understanding of the original spec for C-l was center the current line
vertically in the buffer.

I apologize if I have left any system information out or if this is 
a duplicate bug.  If you could tell me whether this is a bug, or if
it is fixed in 21.2.2, I would really appreciate it.  I could not find
it in the "User Visible Changes" and I did not find a list of known
bugs.

-Kim.

Re: bug in emacs 21.2.1?

[Richard Stallman]

This does not fail for me in the latest development Emacs,
or in the pre-21.3 sources I have.  However, your test case
is not precise; it's possible that it fails in some cases
but not the one I tried.

Please read the Bugs section in the Emacs manual, which provides
guidelines on how to write a bug report to give us the
necessary information so we can fix the bug.