A scrolling problem with Emac trunk

A scrolling problem with Emac trunk

[Angelo Graziosi]

I don't know if this has been already flagged, if it is a new behavior 
or if it is a bug...

Anyway I want to flag for completeness and apologize if it has already 
flagged.

The following regards a GTK build.

Sometimes I need to have two views of the same (long) buffer. Suppose I 
have a text buffer of 200 lines and I need a view of the first 25 lines 
and a view of the last 25 lines. Usually I do this opening another 
frame, C-x 5 2, and scrolling (with mouse wheel or the scroll bar) so to 
have the two views.

With current trunk (rev. 111253) this does not work any more.. To be 
short, when I scroll in a frame the other scrolls almost in the same way 
so that both frames shows the same view... It is impossible to have 
different views of a long buffer.

Instead, the trunk rev. 111175 seems to behave correctly and I can have 
two different views in two frames of the same long buffer.


Ciao,
  Angelo.

Re: A scrolling problem with Emac trunk

[martin rudalics]

 > Sometimes I need to have two views of the same (long) buffer. Suppose I
 > have a text buffer of 200 lines and I need a view of the first 25 lines
 > and a view of the last 25 lines. Usually I do this opening another
 > frame, C-x 5 2, and scrolling (with mouse wheel or the scroll bar) so to
 > have the two views.
 >
 > With current trunk (rev. 111253) this does not work any more.. To be
 > short, when I scroll in a frame the other scrolls almost in the same way
 > so that both frames shows the same view... It is impossible to have
 > different views of a long buffer.
 >
 > Instead, the trunk rev. 111175 seems to behave correctly and I can have
 > two different views in two frames of the same long buffer.

Same here on Windows XP for some value of "almost".  Irreproducible with
Emacs -Q.  Does it happen with Emacs -Q on your system?

FWIW, here the buffer in the "other" frame does not scroll but its
window's modeline values change to the same as in the other frame.
Maybe Stefan's attempt to synchronize selected frame and selected window
misfired.  Pure speculation, of course.

martin

Re: A scrolling problem with Emac trunk

[Xue Fuqiao]

On Mon, 17 Dec 2012 14:39:00 +0100
martin rudalics <rudalics@gmx.at> wrote:

> Same here on Windows XP for some value of "almost".  Irreproducible with
> Emacs -Q.  Does it happen with Emacs -Q on your system?

It also happens on my system:
GNU Emacs 24.3.50.1 (x86_64-pc-linux-gnu, GTK+ Version 2.24.13) of 2012-12-17 on Emacs

But not in the Emacs pretest 24.2.91.

-- 
Best regards, Xue Fuqiao.
http://www.emacswiki.org/emacs/XueFuqiao

Re: A scrolling problem with Emac trunk

[martin rudalics]

Verified.  The problem is due to

revno: 111232
committer: Stefan Monnier <monnier@iro.umontreal.ca>
branch nick: trunk
timestamp: Fri 2012-12-14 10:52:43 -0500
message:
   * src/xdisp.c (display_mode_lines): Keep selected_window and selected_frame
   in sync.

Reverting this change and the subsequent

revno: 111232
committer: Stefan Monnier <monnier@iro.umontreal.ca>
branch nick: trunk
timestamp: Fri 2012-12-14 10:52:43 -0500
message:
   * src/xdisp.c (display_mode_lines): Keep selected_window and selected_frame
   in sync.

makes the problem disappear.

martin

Re: A scrolling problem with Emac trunk

[Stefan Monnier]

>   * src/xdisp.c (display_mode_lines): Keep selected_window and selected_frame
>   in sync.
> Reverting this change and the subsequent

Could someone who understands the redisplay code better than I figure
out why the above change causes those problems?


        Stefan

Re: A scrolling problem with Emac trunk

[Stefan Monnier]

> revno: 111232
> committer: Stefan Monnier <monnier@iro.umontreal.ca>
> branch nick: trunk
> timestamp: Fri 2012-12-14 10:52:43 -0500
> message:
>   * src/xdisp.c (display_mode_lines): Keep selected_window and selected_frame
>   in sync.

It's actually the 111231 that's the problem (it's probably what you
meant).

Changing selected_window without sync'ing point is at the root of
the problem.  Often it's not a problem because we set selected-window
back to its previous value before it can cause problems, but in the
select_frame_for_redisplay that's not the case if redisplay moves point
(as it does when it needs to scroll).

I believe it's fixed now.


        Stefan

Re: A scrolling problem with Emac trunk

[Eli Zaretskii]

> From: Stefan Monnier <monnier@iro.umontreal.ca>
> Date: Mon, 17 Dec 2012 13:02:05 -0500
> Cc: emacs <emacs-devel@gnu.org>, Angelo Graziosi <angelo.graziosi@alice.it>
> 
> >   * src/xdisp.c (display_mode_lines): Keep selected_window and selected_frame
> >   in sync.
> > Reverting this change and the subsequent
> 
> Could someone who understands the redisplay code better than I figure
> out why the above change causes those problems?

I will try.

Re: A scrolling problem with Emac trunk

[Angelo Graziosi]

Ciao Martin,

Il 17/12/2012 14.39, martin rudalics ha scritto:

>
> Same here on Windows XP for some value of "almost".  Irreproducible with
> Emacs -Q.  Does it happen with Emacs -Q on your system?

I can reproduce it also with emacs -Q (here is on Cygwin...)


Ciao,
  Angelo.

Re: A scrolling problem with Emac trunk

[martin rudalics]

> It's actually the 111231 that's the problem (it's probably what you
> meant).

Yes.

> Changing selected_window without sync'ing point is at the root of
> the problem.  Often it's not a problem because we set selected-window
> back to its previous value before it can cause problems, but in the
> select_frame_for_redisplay that's not the case if redisplay moves point
> (as it does when it needs to scroll).

I see.

> I believe it's fixed now.

Works here so far.  But I usually never use more than one frame
so I leave it to the others to tell.  Thanks for the fix.

martin

Re: A scrolling problem with Emac trunk

[Angelo Graziosi]

Ciao Martin,

Il 17/12/2012 22.28, martin rudalics ha scritto:
>
> Works here so far.  But I usually never use more than one frame
> so I leave it to the others to tell.  Thanks for the fix.

Works here too.. Anyway, now I notice that, switching from a frame to 
the other (i.e. moving the mouse pointer and clicking), in the abandoned 
frame, the text is selected below the cursor position...

The screenshot I have prepare is about 600K, so I will send it only to a 
few of you..

Ciao,
Angelo.

Re: A scrolling problem with Emac trunk

[martin rudalics]

> Works here too.. Anyway, now I notice that, switching from a frame to 
> the other (i.e. moving the mouse pointer and clicking), in the abandoned 
> frame, the text is selected below the cursor position...

Can't observe that.  But I'm raising frames automatically.

OTOH here both modelines get highlighted as if both windows
were selected.

martin

Re: A scrolling problem with Emac trunk

[Angelo Graziosi]

Il 18/12/2012 11.57, Angelo Graziosi ha scritto:
> Ciao Martin,
>
> Il 17/12/2012 22.28, martin rudalics ha scritto:
>>
>> Works here so far.  But I usually never use more than one frame
>> so I leave it to the others to tell.  Thanks for the fix.
>
> Works here too.. Anyway, now I notice that, switching from a frame to
> the other (i.e. moving the mouse pointer and clicking), in the abandoned
> frame, the text is selected below the cursor position...
>
> The screenshot I have prepare is about 600K, so I will send it only to a
> few of you..

 From bug #13225 Martin Rudalics and Eli Zaretskii wrote

M.
 > There might still be glitches with the region as Angelo mentioned in 
 > the previous thread

E.
> Could someone please post a complete precise recipe, starting from
> "emacs -Q"?

The glitches have gone in rev. 111279, so I think what I noticed is 
fixed. I think we don't need any more a precise recipe... :-)

Thank you,
  Angelo.

Re: A scrolling problem with Emac trunk

[Eli Zaretskii]

> Date: Thu, 20 Dec 2012 19:49:36 +0100
> From: Angelo Graziosi <angelo.graziosi@alice.it>
> 
> > Works here too.. Anyway, now I notice that, switching from a frame to
> > the other (i.e. moving the mouse pointer and clicking), in the abandoned
> > frame, the text is selected below the cursor position...
> >
> > The screenshot I have prepare is about 600K, so I will send it only to a
> > few of you..
> 
>  From bug #13225 Martin Rudalics and Eli Zaretskii wrote
> 
> M.
>  > There might still be glitches with the region as Angelo mentioned in 
>  > the previous thread
> 
> E.
> > Could someone please post a complete precise recipe, starting from
> > "emacs -Q"?
> 
> The glitches have gone in rev. 111279, so I think what I noticed is 
> fixed. I think we don't need any more a precise recipe... :-)

OK, thanks.