Subject: bug#1166: 23.0.60; Point jumps instead of scrolling in the new line

From: "Lennart Borgman (gmail)" <[email-masked]>
Date: Tue, 14 Oct 2008 19:57:27 +0200

I have found a bug where point jumps to a new postion instead of a new
line beeing scrolled into the selected window. I am unable to narrow it
down, but I can reproduce it (but I am not sure about what makes it
happens). Just to get some thoughts I write down what I have seen so far
here.

The scenario is this:
- Point is on the last line in the window.
- I press "o" in viper. This opens a line below the current line and
puts the point on this line.

What I expect to happen is that this new line is scrolled into the
window. Sometimes this happens. Sometimes instead point jumps up, maybe
10 lines (I did not count them at all) and the window is not scrolled so
the new line is not visible.

There are some other ingredients too:
- I believe that nxml-mode (or a derivative) must be the major mode.
- If I remove nxml-after-change from after-change-functions the bug
disappears.
- If I try to use edebug it also disappears.

Maybe those ingredients also are required, I am not sure since I can't
easily reproduce the bug yet:
- visual-line-mode.

Does anyone have any idea of how to find out what the problem is? In
nxml-after-change there is a whole bunch of "save-*" macros. I commented
out them all, but the bug still appears. But where is the scrolling done?

(Note that I am using my patched version right now when investigating
the bugs, but I do not think it matters here.)

In GNU Emacs 23.0.60.1 (i386-mingw-nt5.1.2600)
 of 2008-10-14 (patched)
Windowing system distributor `Microsoft Corp.', version 5.1.2600
configured using `configure --with-gcc (3.4) --cflags -Ic:/g/include'