bug#12811: 24.3.50; `scroll-up/down-aggressively' don't seem to work as expected

[Dani Moncayo]

Maybe I'm missing something, but after reading (info "(emacs) Auto
Scrolling") and the docstrings of the variables
`scroll-up/down-aggressively', the behavior I observe after playing a
bit doesn't seem right to me.

Recipe from "emacs -Q":
1. Visit the attached file.
2. Adjust the height of the Emacs GUI frame so that only lines 1 to 11
are visible.  With this setup it is easy to tell the relative position
of a line in the window in terms of percentage from the top or bottom,
since each line counts as 10% for such percentages.
3. Go to line 1.
4. Type: C-u 1 5 C-n
--> Point goes to line 16, and that line is centered in the window. So
everything is as expected so far.
5. M-: (setq scroll-up-aggressively 0.7) <RET>
6. Repeat steps #3 and #4.
--> This time I observe that point goes to line 16, but that line is
near the bottom of the window (9th line; 20% from the bottom) when it
should be near the top (4th line; 70% from the bottom).


I also observe a misbehavior when testing scroll-down-aggressively:
1. M-: (setq scroll-down-aggressively 0.7) <RET>
2. Go to line 30 and make that line the last visible one.
3. Type: C-u 1 1 C-p
--> I observe that point goes to line 19, but that line is the 10th in
the window (90% from the top), when it should be the 8th line (70%
from the top).


In GNU Emacs 24.3.50.1 (i386-mingw-nt6.1.7601)
 of 2012-11-05 on MS-W7-DANI
Bzr revision: 110809 lekktu@gmail.com-20121105172930-a5gn0bwi4lndchhw
Windowing system distributor `Microsoft Corp.', version 6.1.7601
Configured using:
 `configure --with-gcc (4.7) --no-opt --enable-checking --cflags
 -I../../libs/libXpm-3.5.10/include -I../../libs/libXpm-3.5.10/src
 -I../../libs/libpng-1.2.37-lib/include -I../../libs/zlib-1.2.5
 -I../../libs/giflib-4.1.4-1-lib/include
 -I../../libs/jpeg-6b-4-lib/include
 -I../../libs/tiff-3.8.2-1-lib/include
 -I../../libs/libxml2-2.7.8-w32-bin/include/libxml2
 -I../../libs/gnutls-3.0.9-w32-bin/include
 -I../../libs/libiconv-1.9.2-1-lib/include'

Important settings:
  value of $LANG: ESN
  locale-coding-system: cp1252
  default enable-multibyte-characters: t


-- 
Dani Moncayo

test.txt
Description: Text document