From: Anders Lindgren <andlind@gmail.com>
To: martin rudalics <rudalics@gmx.at>
Cc: 15957@debbugs.gnu.org
Subject: bug#15957: 24.3.50; Follow mode scrolling broken on Emacs trunk
Date: Sat, 23 Nov 2013 23:01:24 +0100 [thread overview]
Message-ID: <CABr8ebZBUWzCWpca=M=KTARXZCooADu0Uy5bVwBE6S=9SxjOzQ@mail.gmail.com> (raw)
In-Reply-To: <52909877.1070203@gmx.at>
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Hi!
No, the actual numbers don't appear to be important. I simply picked some
numbers to make sure the frame was wide enough for two side-by-side
windows. I tried 40 instead of 70 and you get the same effect.
I really doubt that the code in `follow-scroll-up' is broken. Follow-mode
is designed so that the rearrangement of the other windows (the ones that
follow the selected window) occur in the post-command hook (to allow
Follow-mode to act upon all Emacs commands, not only it's special
function). It appears that something has changed in the display engine, or
in the way that post-command-hook is called, that makes this mechanism
fail. This could also account for the difference we see when the function
is called via a key sequence as compared to via M-x.
This is also the reason why reported this as a bug, rather than digging
into the code myself. However, I could try to add log code to Follow mode,
to check if I could try to figure out what is going on.
-- Anders
On Sat, Nov 23, 2013 at 12:58 PM, martin rudalics <rudalics@gmx.at> wrote:
> Hi Anders
>
> > Scrolling multiple pages when Follow mode is enabled sometimes fails.
> >
> > Steps to repeat:
> >
> > Emacs -Q
> > C-h t
> > ESC : (set-frame-size (selected-frame) 200 70) RET
>
> Is this really necessary? 70 lines means I can't see my echo area any
> more.
>
> > M-x follow-delete-other-windows-and-split RET
> > C-c . C-v
> >
> > The intent is to scroll the entire document two pages down, the left
> > window should still be selected (this causes Follow mode to arrange the
> > right window after it). Instead, the right window is selected,
>
> Can you tell when and where the window on the right is selected?
>
> > which causes
> > the left to be arranged after it, effectively undoing the scroll.
>
> IIUC `follow-scroll-up' should select the proper window via
>
> (let* ((windows (follow-all-followers))
> (end (window-end (car (reverse windows)))))
> (if (eq end (point-max))
> (signal 'end-of-buffer nil)
> (select-window (car windows))
>
> which seems to imply that `follow-all-followers' doesn't return what it
> is supposed to. Am I correct that the first window returned by the
> latter should be `frame-first-window'? In that case try to replace the
> last line of `follow-all-followers' by something like
>
> (prog1
> (setq windows (sort windows 'follow--window-sorter))
> (unless (eq (car windows) (frame-first-window (window-frame win)))
> (error "Bad windows %s" windows)))))
>
> and maybe this way we can find out whether the problem is there.
>
> > The problem seems to be sometimes intermittent, sometimes the scroll
> works,
> > sometimes it don't.
> >
> > An interesting effect is that the problem only occurs when
> > follow-scroll-up is bound to a key. When issuing M-x follow-scroll-up
> > RET, the command seems to be working properly.
>
> I have no idea why this could change the course of things because ARG
> should be nil in both cases.
>
> > By the way, I'm the original author of Follow mode, even tough I haven't
> > touched it for many years.
>
> I suppose you should touch it again ;-)
>
> martin
>
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next prev parent reply other threads:[~2013-11-23 22:01 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-11-22 22:23 bug#15957: 24.3.50; Follow mode scrolling broken on Emacs trunk Anders Lindgren
2013-11-23 11:58 ` martin rudalics
2013-11-23 22:01 ` Anders Lindgren [this message]
2013-11-24 10:10 ` martin rudalics
2013-11-25 9:19 ` Anders Lindgren
[not found] ` <CABr8ebbnxDgVF-+pdk955Ux-SQuZDONw=OhHOVUdO9d=xsTcZg@mail.gmail.com>
2013-11-25 16:42 ` martin rudalics
2013-11-26 6:33 ` Dmitry Antipov
2013-11-26 11:01 ` Anders Lindgren
2013-11-26 14:12 ` martin rudalics
2013-11-26 14:25 ` Anders Lindgren
2013-11-26 16:19 ` martin rudalics
2013-11-26 17:03 ` Anders Lindgren
2013-11-26 17:21 ` martin rudalics
2013-11-27 7:48 ` martin rudalics
2014-01-04 14:12 ` martin rudalics
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