bug#5489: 23.1.91; scroll bar redisplay problem

bug#5489: 23.1.91; scroll bar redisplay problem

[Stephen Berman]

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Some change since the pretest started has resulted in a redisplay
problem with the scroll bar.  I have been able to reproduce it only with
the third party library tabbar.el (available from
http://emhacks.cvs.sourceforge.net/viewvc/*checkout*/emhacks/emhacks/tabbar.el?revision=1.69).
Here is a minimal recipe:

1. Let ~/.emacs consist of the following lines:

(load "/path/to/tabbar.el")
(tabbar-mode 1)

2. emacs

3. C-h f RET help RET

=> Now the frame is split vertically, and the lower window contains no scroll
bar.  Here is a screenshot:


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I have also observed this in other split window configurations, e.g. the
Summary and Article buffers in Gnus.  The missing scroll bar appears as
soon as the lower window is made current.  I have also seen the scroll
appear spontaneously after a few seconds, but I haven't found a way to
reproduce that.  The bug occurs only if the above sexps are in
user-init-file; it does not occur after evalling them after starting
with -Q, or loading them from the command line.

This bug is present in all pretest builds I have, but the earliest of
these is only from 2010-01-13.  It is not present in the last
pre-pretest build I have, from 2009-11-27.

I don't know how to debug this, but if someone can guide me, I'll try.


In GNU Emacs 23.1.91.4 (i686-pc-linux-gnu, GTK+ Version 2.18.1)
 of 2010-01-28 on escher
Windowing system distributor `The X.Org Foundation', version 11.0.10605000
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: en_US.UTF-8
  value of $XMODIFIERS: @im=local
  locale-coding-system: utf-8-unix
  default enable-multibyte-characters: t

bug#5489: 23.1.91; scroll bar redisplay problem

[Stephen Berman]

On Thu, 28 Jan 2010 23:50:06 +0100 Stephen Berman <stephen.berman@gmx.net> wrote:

> Some change since the pretest started has resulted in a redisplay
> problem with the scroll bar.  I have been able to reproduce it only with
> the third party library tabbar.el (available from
> http://emhacks.cvs.sourceforge.net/viewvc/*checkout*/emhacks/emhacks/tabbar.el?revision=1.69).
> Here is a minimal recipe:
>
> 1. Let ~/.emacs consist of the following lines:
>
> (load "/path/to/tabbar.el")
> (tabbar-mode 1)
>
> 2. emacs
>
> 3. C-h f RET help RET
>
> => Now the frame is split vertically, and the lower window contains no scroll
> bar.

When I read the report of bug#5571, I suspected it and the above were
probably the same, and indeed, setting GDK_NATIVE_WINDOWS=1 prevents the
scroll bar disappearance in my recipe above.  What's more, Jan D.'s fix
for bug#5571 also fixes my bug (at least, with it the recipe above fails
to make the scroll bar vanish).  Since no one has commented on this bug,
I feel entitled to close it.  Thanks for the fix.

Steve Berman