bug#20607: 24.5; Problem with overlays at same position but in different windows

bug#20607: 24.5; Problem with overlays at same position but in different windows

[Oleh Krehel]

Suppose I have two windows, WND1 and WND2, both displaying the same
buffer. In WND1, there's an overlay from 1 to 2 with window property
WND1 and display "ab". In WND2, there's an overlay from 1 to 3 with
window property WND2 and display "abc".

Instead of the expected, I see "ab" in WND1, but "abcabc" in WND2.  When
I `move-overlay' in the first window to 1-3, the glitch disappears, but
I actually want the overlay to be 1-2, not 1-3. If I have to make it
1-3, I'd have to modify the display as well to include one more
character from the buffer. I think it's better to fix the overlay logic
rather than go for this work-around.

Oleh

bug#20607: 24.5; Problem with overlays at same position but in different windows

[Eli Zaretskii]

> From: Oleh Krehel <ohwoeowho@gmail.com>
> Date: Mon, 18 May 2015 20:29:10 +0200
> 
> 
> Suppose I have two windows, WND1 and WND2, both displaying the same
> buffer. In WND1, there's an overlay from 1 to 2 with window property
> WND1 and display "ab". In WND2, there's an overlay from 1 to 3 with
> window property WND2 and display "abc".
> 
> Instead of the expected, I see "ab" in WND1, but "abcabc" in WND2.  When
> I `move-overlay' in the first window to 1-3, the glitch disappears, but
> I actually want the overlay to be 1-2, not 1-3. If I have to make it
> 1-3, I'd have to modify the display as well to include one more
> character from the buffer. I think it's better to fix the overlay logic
> rather than go for this work-around.

Please show the code to reproduce this.

bug#20607: 24.5; Problem with overlays at same position but in different windows

[Oleh Krehel]

Eli Zaretskii <eliz@gnu.org> writes:

>> From: Oleh Krehel <ohwoeowho@gmail.com>
>> Date: Mon, 18 May 2015 20:29:10 +0200
>> 
>> 
>> Suppose I have two windows, WND1 and WND2, both displaying the same
>> buffer. In WND1, there's an overlay from 1 to 2 with window property
>> WND1 and display "ab". In WND2, there's an overlay from 1 to 3 with
>> window property WND2 and display "abc".
>> 
>> Instead of the expected, I see "ab" in WND1, but "abcabc" in WND2.  When
>> I `move-overlay' in the first window to 1-3, the glitch disappears, but
>> I actually want the overlay to be 1-2, not 1-3. If I have to make it
>> 1-3, I'd have to modify the display as well to include one more
>> character from the buffer. I think it's better to fix the overlay logic
>> rather than go for this work-around.
>
> Please show the code to reproduce this.

Split the frame into 3 windows, two of them on *scratch*. In the third
window, evaluate this:

(let* ((wl (window-list))
       (w1 (nth 1 wl))
       (w2 (nth 2 wl))
       o1 o2)
  (with-current-buffer "*scratch*"
    (insert "asdf"))
  (with-selected-window w1
    (setq o1 (make-overlay 1 2))
    (overlay-put o1 'window w1)
    (overlay-put o1 'display "ok"))
  (with-selected-window w2
    (setq o2 (make-overlay 1 3))
    (overlay-put o2 'window w2)
    (overlay-put o2 'display "try")))

bug#20607: 24.5; Problem with overlays at same position but in different windows

[Eli Zaretskii]

> Date: Mon, 18 May 2015 21:59:26 +0300
> From: Eli Zaretskii <eliz@gnu.org>
> Cc: 20607@debbugs.gnu.org
> 
> > From: Oleh Krehel <ohwoeowho@gmail.com>
> > Date: Mon, 18 May 2015 20:29:10 +0200
> > 
> > 
> > Suppose I have two windows, WND1 and WND2, both displaying the same
> > buffer. In WND1, there's an overlay from 1 to 2 with window property
> > WND1 and display "ab". In WND2, there's an overlay from 1 to 3 with
> > window property WND2 and display "abc".
> > 
> > Instead of the expected, I see "ab" in WND1, but "abcabc" in WND2.  When
> > I `move-overlay' in the first window to 1-3, the glitch disappears, but
> > I actually want the overlay to be 1-2, not 1-3. If I have to make it
> > 1-3, I'd have to modify the display as well to include one more
> > character from the buffer. I think it's better to fix the overlay logic
> > rather than go for this work-around.
> 
> Please show the code to reproduce this.

Actually, you need not bother: I see it here.

For now, all I can say is that this is very old: Emacs 22 already
behaves like that.  I think the problem is that the display engine
bumps into the same overlay twice while walking the buffer, but I need
to take a closer look to be sure.

bug#20607: 24.5; Problem with overlays at same position but in different windows

[Eli Zaretskii]

> Date: Mon, 18 May 2015 22:14:20 +0300
> From: Eli Zaretskii <eliz@gnu.org>
> Cc: 20607@debbugs.gnu.org
> 
> > > Suppose I have two windows, WND1 and WND2, both displaying the same
> > > buffer. In WND1, there's an overlay from 1 to 2 with window property
> > > WND1 and display "ab". In WND2, there's an overlay from 1 to 3 with
> > > window property WND2 and display "abc".
> > > 
> > > Instead of the expected, I see "ab" in WND1, but "abcabc" in WND2.  When
> > > I `move-overlay' in the first window to 1-3, the glitch disappears, but
> > > I actually want the overlay to be 1-2, not 1-3. If I have to make it
> > > 1-3, I'd have to modify the display as well to include one more
> > > character from the buffer. I think it's better to fix the overlay logic
> > > rather than go for this work-around.
> > 
> > Please show the code to reproduce this.
> 
> Actually, you need not bother: I see it here.
> 
> For now, all I can say is that this is very old: Emacs 22 already
> behaves like that.  I think the problem is that the display engine
> bumps into the same overlay twice while walking the buffer, but I need
> to take a closer look to be sure.

Fixed in commit 18338b1, which also includes a fix to a related subtle
problem with cursor movement in this case (you couldn't put point at
position 2 in WND1 window: it would be "adjusted" to position 3).

bug#20607: 24.5; Problem with overlays at same position but in different windows

[Oleh Krehel]

Eli Zaretskii <eliz@gnu.org> writes:

> Fixed in commit 18338b1, which also includes a fix to a related subtle
> problem with cursor movement in this case (you couldn't put point at
> position 2 in WND1 window: it would be "adjusted" to position 3).

Thanks, I confirm that the change works fine for me.