24.2.90: Confusion in "Top" "nn%" and "Bot".

24.2.90: Confusion in "Top" "nn%" and "Bot".

[Alan Mackenzie]

Hi, Emacs.

Forgive me if this has been discussed already; is it a feature or a bug?

1. Display an info page (e.g. "Special Input for Incremental Search")
which fits entirely on the screen (if only just).

2. Note that "Top" rather than the expected "All" is displayed.

3. Scroll the text upwards 6 lines.

4. Now, "9%" rather than "Bot" is displayed.

5. Scroll the text repeatedly upwards.  "nn%" continues to be displayed,
despite the fact that the bottom of the buffer is visible.

6. When the last visible line is scrolled off the window, finally, "Bot"
is displayed.

I think either this behaviour or the manual is buggy.

-- 
Alan Mackenzie (Nuremberg, Germany).

Re: 24.2.90: Confusion in "Top" "nn%" and "Bot".

[Dani Moncayo]

> 1. Display an info page (e.g. "Special Input for Incremental Search")
> which fits entirely on the screen (if only just).

In my laptop, that info node doesn't fit entirely on the screen, but
if I try with its parent node, for example ("(emacs) Incremental
Search") which does fit, I observe the problem you mention: "Top" in
the modeline instead of the expected "All".

> 2. Note that "Top" rather than the expected "All" is displayed.
>
> 3. Scroll the text upwards 6 lines.
>
> 4. Now, "9%" rather than "Bot" is displayed.
>
> 5. Scroll the text repeatedly upwards.  "nn%" continues to be displayed,
> despite the fact that the bottom of the buffer is visible.
>
> 6. When the last visible line is scrolled off the window, finally, "Bot"
> is displayed.
>
> I think either this behaviour or the manual is buggy.

Yes, there is a bug somewhere, and is a regression: the 24.2 release does TRT.

I've tried with another manual (GNU Make) and I see the problem there
too (with the trunk, not with the 24.2  release).

So the problem seems to be in Emacs, not in the manual.

HTH

-- 
Dani Moncayo

Re: 24.2.90: Confusion in "Top" "nn%" and "Bot".

[Andreas Schwab]

This is triggered by the invisible text property at the end of the
narrowed region.  When removing it from the buffer the percentage
display works correctly again.

(with-current-buffer (get-buffer-create "*test*")
  (insert #("a\nb\n" 2 4 (invisible t)))
  (display-buffer (current-buffer)))

Andreas.

-- 
Andreas Schwab, schwab@linux-m68k.org
GPG Key fingerprint = 58CA 54C7 6D53 942B 1756  01D3 44D5 214B 8276 4ED5
"And now for something completely different."

Re: 24.2.90: Confusion in "Top" "nn%" and "Bot".

[Eli Zaretskii]

> From: Andreas Schwab <schwab@linux-m68k.org>
> Date: Sat, 01 Dec 2012 14:06:08 +0100
> Cc: emacs-devel@gnu.org
> 
> This is triggered by the invisible text property at the end of the
> narrowed region.  When removing it from the buffer the percentage
> display works correctly again.

A simple fix is not to hide the last newline.  This is from the end of
Info-fontify-node:

      ;; Hide empty lines at the end of the node.
      (goto-char (point-max))
      (skip-chars-backward "\n")
      (when (< (1+ (point)) (1- (point-max)))
	(put-text-property (1+ (point)) (1- (point-max)) 'invisible t))

where I decremented point-max in 2 last instances.

Re: 24.2.90: Confusion in "Top" "nn%" and "Bot".

[Juri Linkov]

> A simple fix is not to hide the last newline.  This is from the end of
> Info-fontify-node:
>
>       ;; Hide empty lines at the end of the node.
>       (goto-char (point-max))
>       (skip-chars-backward "\n")
>       (when (< (1+ (point)) (1- (point-max)))
> 	(put-text-property (1+ (point)) (1- (point-max)) 'invisible t))
>
> where I decremented point-max in 2 last instances.

This will display 2 empty lines defeating the request of bug#12272.
I'll post another patch to bug#12272.