bug#2996: 23.0.92; Scrolling narrows region

bug#2996: 23.0.92; Scrolling narrows region

[Sebastian Rose]

Please write in English if possible, because the Emacs maintainers
usually do not have translators to read other languages for them.

Your bug report will be posted to the emacs-pretest-bug@gnu.org mailing list.

Please describe exactly what actions triggered the bug
and the precise symptoms of the bug:


I have `transient-mark-mode t'

When I right click into a buffer that creates an active region.
If I now scroll down and right click again, the active region is
extended as expected.

If I keep on scrolling and right-clicking, so that the start of the
regions scrolls off the window, the region is truncated and now starts
on the first visible line.

Not sure, if this behaviour is expected, but it's different from what
emacs22 did.

Also, this is very surprising, since pasting the region into another
bufer through middle-click, does not paste what I expected. Thus messing
up the target buffer and causing data loss that way.




If Emacs crashed, and you have the Emacs process in the gdb debugger,
please include the output from the following gdb commands:
    `bt full' and `xbacktrace'.
If you would like to further debug the crash, please read the file
/usr/local/share/emacs/23.0.92/etc/DEBUG for instructions.


In GNU Emacs 23.0.92.1 (i686-pc-linux-gnu, GTK+ Version 2.14.7)
 of 2009-04-09 on kassiopeya
Windowing system distributor `The X.Org Foundation', version 11.0.10402000
Important settings:
  value of $LC_ALL: nil
  value of $LC_COLLATE: nil
  value of $LC_CTYPE: nil
  value of $LC_MESSAGES: nil
  value of $LC_MONETARY: nil
  value of $LC_NUMERIC: nil
  value of $LC_TIME: nil
  value of $LANG: de_DE.UTF-8
  value of $XMODIFIERS: nil
  locale-coding-system: utf-8-unix
  default-enable-multibyte-characters: t

Major mode: Article

Minor modes in effect:
  recentf-mode: t
  yas/minor-mode: t
  show-paren-mode: t
  global-hl-line-mode: t
  display-time-mode: t
  desktop-save-mode: t
  auto-image-file-mode: t
  tooltip-mode: t
  mouse-wheel-mode: t
  menu-bar-mode: t
  file-name-shadow-mode: t
  global-font-lock-mode: t
  font-lock-mode: t
  global-auto-composition-mode: t
  auto-composition-mode: t
  auto-encryption-mode: t
  auto-compression-mode: t
  column-number-mode: t
  line-number-mode: t
  transient-mark-mode: t

Recent input:
<up> <up> <up> <down> E <up> <up> E <up> E SPC E E 
E E E E E E E E E E SPC B C-M-e y SPC SPC B C-g B C-M-e 
y C-g B <delete> y SPC SPC E E E E E B C-M-e y SPC 
SPC SPC SPC SPC SPC E SPC <help-echo> <down-mouse-5> 
<mouse-5> <down-mouse-5> <mouse-5> <down-mouse-5> <mouse-5> 
<double-down-mouse-5> <double-mouse-5> <down-mouse-5> 
<mouse-5> <double-down-mouse-5> <double-mouse-5> <triple-down-mouse-5> 
<triple-mouse-5> <triple-down-mouse-5> <triple-mouse-5> 
<triple-down-mouse-5> <triple-mouse-5> <down-mouse-4> 
<mouse-4> <double-down-mouse-4> <double-mouse-4> <down-mouse-4> 
<mouse-4> <double-down-mouse-4> <double-mouse-4> <triple-down-mouse-4> 
<triple-mouse-4> <down-mouse-4> <mouse-4> <double-down-mouse-4> 
<double-mouse-4> <triple-down-mouse-4> <triple-mouse-4> 
<down-mouse-5> <mouse-5> <down-mouse-5> <mouse-5> <double-down-mouse-5> 
<double-mouse-5> <down-mouse-4> <mouse-4> <down-mouse-5> 
<mouse-5> <double-down-mouse-5> <double-mouse-5> <down-mouse-5> 
<mouse-5> <double-down-mouse-5> <double-mouse-5> <help-echo> 
<down-mouse-1> <mouse-1> <help-echo> B C-M-e y SPC 
SPC SPC SPC SPC SPC 1 0 0 <return> M-> <up> <up> <up> 
<up> <up> <up> <up> SPC <down> <down> SPC <up> SPC 
<down> SPC <up> SPC R <up> <delete> <down-mouse-5> 
<mouse-5> <down-mouse-5> <mouse-5> <double-down-mouse-5> 
<double-mouse-5> <down-mouse-5> <mouse-5> <double-down-mouse-5> 
<double-mouse-5> <down-mouse-5> <mouse-5> <down-mouse-4> 
<mouse-4> <double-down-mouse-4> <double-mouse-4> <triple-down-mouse-4> 
<triple-mouse-4> <triple-down-mouse-4> <triple-mouse-4> 
<down-mouse-4> <mouse-4> <double-down-mouse-4> <double-mouse-4> 
<down-mouse-1> <mouse-1> <down-mouse-3> <mouse-3> <down-mouse-5> 
<mouse-5> <double-down-mouse-5> <double-mouse-5> <triple-down-mouse-5> 
<triple-mouse-5> <down-mouse-3> <mouse-3> <down-mouse-5> 
<mouse-5> <double-down-mouse-5> <double-mouse-5> <down-mouse-3> 
<mouse-3> <double-down-mouse-3> <double-mouse-3> <down-mouse-4> 
<mouse-4> <double-down-mouse-4> <double-mouse-4> <triple-down-mouse-4> 
<triple-mouse-4> <down-mouse-3> <mouse-3> <double-down-mouse-3> 
<double-mouse-3> <return> <return> s o r r <backspace> 
<backspace> <backspace> <backspace> S o r r x <backspace> 
y , SPC r <M-backspace> <M-backspace> C-x k <return> 
y C-x k C-g SPC SPC C-g <down> SPC <help-echo> <down-mouse-5> 
<mouse-5> <down-mouse-5> <mouse-5> <down-mouse-5> <mouse-5> 
<down-mouse-5> <mouse-5> <down-mouse-5> <mouse-5> <double-down-mouse-5> 
<double-mouse-5> <down-mouse-5> <mouse-5> <double-down-mouse-5> 
<double-mouse-5> <down-mouse-5> <mouse-5> <double-down-mouse-5> 
<double-mouse-5> <down-mouse-5> <mouse-5> <double-down-mouse-5> 
<double-mouse-5> <down-mouse-1> <mouse-1> <down-mouse-1> 
<mouse-1> <down-mouse-1> <mouse-1> <down-mouse-3> <mouse-3> 
<down-mouse-4> <mouse-4> <double-down-mouse-4> <double-mouse-4> 
<down-mouse-3> <mouse-3> <down-mouse-4> <mouse-4> <double-down-mouse-4> 
<double-mouse-4> <down-mouse-4> <mouse-4> <double-down-mouse-4> 
<double-mouse-4> <down-mouse-5> <mouse-5> <double-down-mouse-5> 
<double-mouse-5> <triple-down-mouse-5> <triple-mouse-5> 
<down-mouse-4> <mouse-4> <double-down-mouse-4> <double-mouse-4> 
<triple-down-mouse-4> <triple-mouse-4> M-x r e p o 
r <tab> <return>

Recent messages:
No more unread newsgroups
Retrieving newsgroup: nnml:mail:eingang...
Fetching headers for nnml:mail:eingang...done
Scoring...done
Generating summary...done
No more unread articles
Mark set [3 times]
byte-code: Beginning of buffer [2 times]
Quit
Quit


-- 
Sebastian Rose, EMMA STIL - mediendesign, Niemeyerstr.6, 30449 Hannover
Tel.:  +49 (0)511 - 36 58 472
Fax:   +49 (0)1805 - 233633 - 11044
mobil: +49 (0)173 - 83 93 417
Email: s.rose@emma-stil.de, sebastian_rose@gmx.de
Http:  www.emma-stil.de

bug#2996: 23.0.92; Scrolling narrows region

[Chong Yidong]

> I have `transient-mark-mode t'
>
> When I right click into a buffer that creates an active region.
> If I now scroll down and right click again, the active region is
> extended as expected.
>
> If I keep on scrolling and right-clicking, so that the start of the
> regions scrolls off the window, the region is truncated and now starts
> on the first visible line.

I can't reproduce this.  Did you scroll using the mouse-wheel, the
scroll-bar, or some other method?  Please provide a *precise* set of
instructions for reproducing this bug, starting from emacs -Q.

bug#2996: 23.0.92; Scrolling narrows region

[Sebastian Rose]

Chong Yidong <cyd@stupidchicken.com> writes:
> I can't reproduce this.  Did you scroll using the mouse-wheel, the
> scroll-bar, or some other method?  Please provide a *precise* set of
> instructions for reproducing this bug, starting from emacs -Q.



Yes, sorry for being unclear. I indeed found, that this only happens
when I use the mousewheel (which I always do: scroll-bar-mode nil).


Here's the recipe:

1. emacs -Q

2. C-x C-f file 
   file should contain more than a screenfull of text.

3. Right-click somewhere in the window to produce an active region. If
   you didn't move point before this, the region starts at the very top
   of the buffer.

4. Right-click somewhere further down to see, that the region is
   resized. 

5. Scroll down using the mousewheel, until the point moves. This
   happens, when point touches the upper window border.

   The mark is now moved from the very top of the buffer, to the first
   visible line.


Starting from 2. somewhere towards the end of the buffer and scrolling
up (in step 4.) has the same effect.



Note, that this does _NOT_ happen, when using the scrollbars or C-v.

It _DOES_ happen, when using M-v

This does _NOT_ happen, when I set the mark (C-SPACE).


   | Way to scroll | direction | region is growing |
   |---------------+-----------+-------------------|
   | scrollbar     | down      | t                 |
   | mousewheel    | down      | nil               |
   | C-v           | down      | nil               |
   | scrollbar     | up        | t                 |
   | mousewheel    | up        | nil               |
   | M-v           | up        | nil               |



When the mark is set through C-SPACE:

   | Way to scroll | direction | region is growing |
   |---------------+-----------+-------------------|
   | scrollbar     | down      | t                 |
   | mousewheel    | down      | t                 |
   | C-v           | down      | t                 |
   | scrollbar     | up        | t                 |
   | mousewheel    | up        | t                 |
   | M-v           | up        | t                 |



What I expected to happen:

I simply expected the region to grow in either case (scrollbar, wheel,
C/M-v).

At least, I expected scrollbars and mousewheel to behave the same way.


-- 
Sebastian Rose, EMMA STIL - mediendesign, Niemeyerstr.6, 30449 Hannover
Tel.:  +49 (0)511 - 36 58 472
Fax:   +49 (0)1805 - 233633 - 11044
mobil: +49 (0)173 - 83 93 417
Email: s.rose@emma-stil.de, sebastian_rose@gmx.de
Http:  www.emma-stil.de

bug#2996: 23.0.92; Scrolling narrows region

[martin rudalics]

 > Here's the recipe:
 >
 > 1. emacs -Q
 >
 > 2. C-x C-f file
 >    file should contain more than a screenfull of text.
 >
 > 3. Right-click somewhere in the window to produce an active region. If
 >    you didn't move point before this, the region starts at the very top
 >    of the buffer.
 >
 > 4. Right-click somewhere further down to see, that the region is
 >    resized.
 >
 > 5. Scroll down using the mousewheel, until the point moves. This
 >    happens, when point touches the upper window border.
 >
 >    The mark is now moved from the very top of the buffer, to the first
 >    visible line.

I suppose it's due to that change:

2008-04-08  Chong Yidong  <cyd@stupidchicken.com>

	* mwheel.el (mwheel-scroll): Deactivate any temporarily active
	region if point moves.

Could you try to

(1) check your scenario with `transient-mark-mode' disabled, and

(2) check your scenario with Chong's change reverted?

martin

bug#2996: 23.0.92; Scrolling narrows region

[Chong Yidong]

> 1. emacs -Q
> 2. C-x C-f file 
>    file should contain more than a screenfull of text.
> 3. Right-click somewhere in the window to produce an active region. If
>    you didn't move point before this, the region starts at the very top
>    of the buffer.
> 4. Right-click somewhere further down to see, that the region is
>    resized. 
> 5. Scroll down using the mousewheel, until the point moves. This
>    happens, when point touches the upper window border.
>
>    The mark is now moved from the very top of the buffer, to the first
>    visible line.

When point moves due to scrolling, the mark is deactivated---at least,
that's what I observe.  This does not move the mark; it remains at the
same position as before, just deactivated.  You can verify this with C-x
C-x.

So I don't see any bug here.

bug#2996: 23.0.92; Scrolling narrows region

[Glenn Morris]

I also cannot see a bug here, so I am closing this. If you think there
is still an issue in the latest relase, 23.3, please reply and we can
reopen this if needed.

Chong Yidong wrote:

> When point moves due to scrolling, the mark is deactivated---at least,
> that's what I observe.  This does not move the mark; it remains at the
> same position as before, just deactivated.  You can verify this with C-x
> C-x.
>
> So I don't see any bug here.