bug#8307: Scrolling problems in lexbind-new branch

bug#8307: Scrolling problems in lexbind-new branch

[Juanma Barranquero]

Version: 24.0.50
Package: emacs

I can reproduce this at will on lexbind-new, and not at all on trunk.

Assume you have a test file, test.txt, with many non-empty lines.
That's not really required (it could be any file long enough to cause
scrolling), but makes the bug easier to see.

In case it matters, I'm using DejaVu Sans Mono:

    uniscribe:-outline-DejaVu Sans
Mono-normal-normal-normal-mono-13-*-*-*-c-*-iso8859-1

Now do:

   emacs -Q --eval "(progn (setq scroll-conservatively 1)
(setq-default show-trailing-whitespace t))" test.txt
   <right>
   <down>  ;;; keep it pressed until it starts line-by-line scrolling

(The value of scroll-conservatively is irrelevant, as long as it is
greater than zero.)

What I see is that the cursor stops in the next-to-last line;
scrolling continues normally, but the cursor does not advance to the
last line. (In fact, if you keep it pressed down enough time, it
eventually moves to the last line, but in my setup that can take
several hundred lines.)

Now, with the cursor on the next-to-last line, move it to column 0, so

xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
#xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx       ; # is the cursor position
xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx       ; last line of the window,
line number N

Now <down> moves the cursor to the last line:

xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
#xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx       ; last line of the window,
line number N

And then <right> moves to the right *and* scrolls the window:

xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
x#xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx       ; line number N
xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx       ; last line of the window


Another, likely related effect:

  emacs -Q --eval "(setq-default show-trailing-whitespace t)" test.txt

then keep <down> pressed.

Instead of scrolling to the last line of the window and then
recentering, it starts scrolling line-by-line once the cursor reaches
the middle point of the window height.

bug#8307: Scrolling problems in lexbind-new branch

[Stefan Monnier]

>    emacs -Q --eval "(progn (setq scroll-conservatively 1)
> (setq-default show-trailing-whitespace t))" test.txt
>    <right>
>    <down>  ;;; keep it pressed until it starts line-by-line scrolling

> (The value of scroll-conservatively is irrelevant, as long as it is
> greater than zero.)

> What I see is that the cursor stops in the next-to-last line;
> scrolling continues normally, but the cursor does not advance to the
> last line. (In fact, if you keep it pressed down enough time, it
> eventually moves to the last line, but in my setup that can take
> several hundred lines.)

I cannot reproduce it here.  Maybe it's because I updated the lexbind
branch to be in sync with the trunk.  Can you try it with the latest
lexbind branch?


        Stefan

bug#8307: Scrolling problems in lexbind-new branch

[Juanma Barranquero]

On Mon, Mar 21, 2011 at 18:31, Stefan Monnier <monnier@iro.umontreal.ca> wrote:

> Maybe it's because I updated the lexbind
> branch to be in sync with the trunk.  Can you try it with the latest
> lexbind branch?

I cannot reproduce the bug with the latest lexbind-new, so I'm closing this bug.

    Juanma

bug#8307: Scrolling problems in lexbind-new branch

[Eli Zaretskii]

> From: Juanma Barranquero <lekktu@gmail.com>
> Date: Tue, 22 Mar 2011 00:41:01 +0100
> Cc: 8307-done@debbugs.gnu.org
> 
> On Mon, Mar 21, 2011 at 18:31, Stefan Monnier <monnier@iro.umontreal.ca> wrote:
> 
> > Maybe it's because I updated the lexbind
> > branch to be in sync with the trunk.  Can you try it with the latest
> > lexbind branch?
> 
> I cannot reproduce the bug with the latest lexbind-new, so I'm closing this bug.

Thanks.  But the original one with the infloop is still present, if
you remove the change I asked you to apply, yes?

bug#8307: Scrolling problems in lexbind-new branch

[Juanma Barranquero]

On Tue, Mar 22, 2011 at 20:15, Eli Zaretskii <eliz@gnu.org> wrote:

> Thanks.  But the original one with the infloop is still present, if
> you remove the change I asked you to apply, yes?

That one is not reproducible at will, so I'll have to test lexbind-new
for a while.

    Juanma

bug#8307: Scrolling problems in lexbind-new branch

[Eli Zaretskii]

> From: Juanma Barranquero <lekktu@gmail.com>
> Date: Tue, 22 Mar 2011 20:48:38 +0100
> Cc: 8307@debbugs.gnu.org
> 
> On Tue, Mar 22, 2011 at 20:15, Eli Zaretskii <eliz@gnu.org> wrote:
> 
> > Thanks.  But the original one with the infloop is still present, if
> > you remove the change I asked you to apply, yes?
> 
> That one is not reproducible at will, so I'll have to test lexbind-new
> for a while.

I'd appreciate if you could reproduce on the trunk instead.

bug#8307: Scrolling problems in lexbind-new branch

[Juanma Barranquero]

On Tue, Mar 22, 2011 at 20:59, Eli Zaretskii <eliz@gnu.org> wrote:

> I'd appreciate if you could reproduce on the trunk instead.

OK, I'll try.

    Juanma

bug#8307: Scrolling problems in lexbind-new branch

[Juanma Barranquero]

On Tue, Mar 22, 2011 at 20:15, Eli Zaretskii <eliz@gnu.org> wrote:

> But the original one with the infloop is still present, if
> you remove the change I asked you to apply, yes?

Since lexbind-new was updated I haven't been able to reproduce it
there. In the trunk I didn't see it before, and still I don't see it
now.

So consider the problem fixed, and I'll open a new bug report if I the
bug resurfaces.

    Juanma

bug#8307: Scrolling problems in lexbind-new branch

[Eli Zaretskii]

> From: Juanma Barranquero <lekktu@gmail.com>
> Date: Sat, 26 Mar 2011 00:39:30 +0100
> Cc: 8307@debbugs.gnu.org
> 
> On Tue, Mar 22, 2011 at 20:15, Eli Zaretskii <eliz@gnu.org> wrote:
> 
> > But the original one with the infloop is still present, if
> > you remove the change I asked you to apply, yes?
> 
> Since lexbind-new was updated I haven't been able to reproduce it
> there. In the trunk I didn't see it before, and still I don't see it
> now.
> 
> So consider the problem fixed, and I'll open a new bug report if I the
> bug resurfaces.

I'm trying to determine whether the ZV guard is needed in that loop.
I didn't commit the change I asked you to try, so it is unclear to me
how it was fixed.

bug#8307: Scrolling problems in lexbind-new branch

[Juanma Barranquero]

On Sat, Mar 26, 2011 at 08:49, Eli Zaretskii <eliz@gnu.org> wrote:

> I didn't commit the change I asked you to try

Yes, I know.

> so it is unclear to me how it was fixed.

Apparently something that was originally in the trunk and not
lexbind-new "fixes" it (or hides it). If you want me to try something,
just ask.

    Juanma