Subject: Re: bug#10304: 24.0.92: display bug

From: Lars Magne Ingebrigtsen <[email-masked]>
Date: Tue, 02 Dec 2014 18:01:08 +0100

Eli Zaretskii <[email-masked]> writes:

> Unfortunately, I cannot match either of your two images with the
> corresponding dump of the glyph matrix: there are small
> inconsistencies in both the "OK" and the "not OK" cases.  For example,
> the first image shows "Top L1" in the mode line of the window that
> displays the article, but the matrix dump says:
>
>  68: (1) ' 1:--- . news:g.c.w.arnoldzwicky Austenian humbleb...  Top
> L19 (Article) '
>
> which is line 19.  This is a minor discrepancy, but since there are
> many similar discrepancies, some of which are probably parts of the
> bug, I feel I have no firm ground from which I can begin studying the
> data and making hypotheses about what went wrong.

I may have matched up the wrong bits of the log file or something.  I've
now redone it, but made sure that each log file bit really belongs to
the image.

> Could you please produce 2 sets of screenshot+matrix dump which are
> coherent with each other?  I must be sure that when I see a
> discrepancy, it is part of the bug, not some artifact that needs to be
> ignored.
>
> Also, I don't understand the second screenshot: which parts of it are
> correct and which are bogus?  The text before the image looks
> unfinished, but its continuation, starting with screen line 20, which
> is clearly present in the glyph matrix dump, is not shown.  Are you
> saying that Emacs was supposed to display that continuation, but never
> did, and instead left the old parts on display?

I've produced four screenshots instead, which should make it clearer
what it's supposed to look like, and what's the bug.

First, I've selected the article, and it's displaying the topmost part
of the article, and everything is fine.

Then I've scrolled the article down, and everything is still fine.

redisplay_preserve_echo_area (20)
redisplay_internal 0
update_window: first enabled: 24, last: 23, no_scrolling: 0
NOT updating rest of lines; row = 24 end = 23 fp = 1 ip = 0
update_window NOT preempted
update_window: first enabled: 0, last: 3, no_scrolling: 0
scrolling_window found all rows equal
update_window: first enabled: 0, last: 3, no_scrolling: 0
clear_frame_area: [114 - 569] [1145 - 1158]
update_window marks rows 1 - 3 invalid
update_window NOT preempted
update_window: first enabled: 0, last: 3, no_scrolling: 0
clear_frame_area: [37 - 569] [1145 - 1158]
update_window marks rows 1 - 3 invalid
update_window NOT preempted
redisplay_internal 0
update_window: first enabled: 24, last: 23, no_scrolling: 0
NOT updating rest of lines; row = 24 end = 23 fp = 1 ip = 0
update_window NOT preempted
update_window: first enabled: 0, last: 3, no_scrolling: 0
scrolling_window found all rows equal
expose_frame (0, 0, 578, 1147)
expose_window (1, 1, 576, 286)
expose_window (1, 287, 576, 858)
expose_window (1, 1145, 576, 2)
expose_window (1, 0, 576, 0)
redisplay_internal 0
update_window: first enabled: 24, last: 23, no_scrolling: 0
NOT updating rest of lines; row = 24 end = 23 fp = 1 ip = 0
update_window NOT preempted
update_window: first enabled: 0, last: 3, no_scrolling: 0
scrolling_window found all rows equal
redisplay_preserve_echo_area (8)
redisplay_internal 0
update_window: first enabled: 24, last: 23, no_scrolling: 0
NOT updating rest of lines; row = 24 end = 23 fp = 1 ip = 0
update_window NOT preempted
update_window: first enabled: 0, last: 3, no_scrolling: 0
scrolling_window found all rows equal
redisplay_preserve_echo_area (8)
redisplay_internal 0
update_window: first enabled: 24, last: 23, no_scrolling: 0
NOT updating rest of lines; row = 24 end = 23 fp = 1 ip = 0
update_window NOT preempted
update_window: first enabled: 0, last: 3, no_scrolling: 0
scrolling_window found all rows equal
redisplay_internal 0
0x117b8d0 (*Summary nntp+news.gmane.org:gwene.com.wordpress.arnoldzwicky*): same window start
0x117b8d0 (*Summary nntp+news.gmane.org:gwene.com.wordpress.arnoldzwicky*): 1
0x3b5ada8 (*Article nntp+news.gmane.org:gwene.com.wordpress.arnoldzwicky*): forced window start
update_window: first enabled: 0, last: 23, no_scrolling: 0
scrolling_window found all rows equal
update_window: first enabled: 0, last: 67, no_scrolling: 0
scrolling_window scrolled the display
clear_frame_area: [478 - 569] [313 - 326]
clear_frame_area: [492 - 569] [326 - 339]
clear_frame_area: [506 - 569] [339 - 352]
clear_frame_area: [485 - 569] [352 - 365]
clear_frame_area: [450 - 569] [365 - 379]
clear_frame_area: [492 - 569] [379 - 392]
clear_frame_area: [499 - 569] [392 - 406]
clear_frame_area: [478 - 569] [406 - 420]
clear_frame_area: [16 - 569] [420 - 433]
clear_frame_area: [107 - 569] [433 - 446]
clear_frame_area: [16 - 569] [446 - 459]
clear_frame_area: [471 - 569] [459 - 472]
clear_frame_area: [464 - 569] [472 - 485]
clear_frame_area: [464 - 569] [485 - 498]
clear_frame_area: [86 - 569] [498 - 511]
clear_frame_area: [16 - 569] [511 - 524]
clear_frame_area: [478 - 569] [524 - 537]
clear_frame_area: [506 - 569] [537 - 550]
clear_frame_area: [492 - 569] [550 - 563]
clear_frame_area: [478 - 569] [563 - 576]
clear_frame_area: [485 - 569] [576 - 589]
clear_frame_area: [478 - 569] [589 - 602]
clear_frame_area: [198 - 569] [602 - 615]
clear_frame_area: [16 - 569] [615 - 628]
clear_frame_area: [499 - 569] [628 - 641]
clear_frame_area: [72 - 569] [641 - 654]
clear_frame_area: [16 - 569] [654 - 667]
clear_frame_area: [485 - 569] [667 - 680]
clear_frame_area: [506 - 569] [680 - 693]
clear_frame_area: [247 - 569] [693 - 707]
clear_frame_area: [16 - 569] [707 - 720]
clear_frame_area: [485 - 569] [720 - 733]
clear_frame_area: [471 - 569] [733 - 746]
clear_frame_area: [128 - 569] [746 - 759]
clear_frame_area: [16 - 569] [759 - 772]
clear_frame_area: [506 - 569] [772 - 786]
clear_frame_area: [443 - 569] [786 - 799]
clear_frame_area: [506 - 569] [799 - 812]
clear_frame_area: [478 - 569] [812 - 826]
clear_frame_area: [450 - 569] [826 - 839]
clear_frame_area: [499 - 569] [839 - 853]
clear_frame_area: [408 - 569] [853 - 866]
clear_frame_area: [16 - 569] [866 - 879]
clear_frame_area: [30 - 569] [879 - 892]
clear_frame_area: [16 - 569] [892 - 905]
clear_frame_area: [44 - 569] [905 - 918]
clear_frame_area: [16 - 569] [918 - 931]
clear_frame_area: [16 - 569] [931 - 944]
clear_frame_area: [16 - 569] [944 - 957]
clear_frame_area: [16 - 569] [957 - 970]
clear_frame_area: [16 - 569] [970 - 983]
clear_frame_area: [16 - 569] [983 - 996]
clear_frame_area: [16 - 569] [996 - 1009]
clear_frame_area: [16 - 569] [1009 - 1022]
clear_frame_area: [16 - 569] [1022 - 1035]
clear_frame_area: [16 - 569] [1035 - 1048]
clear_frame_area: [16 - 569] [1048 - 1061]
clear_frame_area: [16 - 569] [1061 - 1074]
clear_frame_area: [16 - 569] [1074 - 1087]
clear_frame_area: [16 - 569] [1087 - 1100]
clear_frame_area: [16 - 569] [1100 - 1113]
clear_frame_area: [16 - 569] [1113 - 1126]
clear_frame_area: [16 - 569] [1126 - 1132]
update_window marks rows 65 - 67 invalid
update_window NOT preempted
update_window: first enabled: 0, last: 3, no_scrolling: 0
clear_frame_area: [16 - 569] [1145 - 1158]
update_window marks rows 1 - 3 invalid
update_window NOT preempted
redisplay_preserve_echo_area (8)
redisplay_internal 0
update_window: first enabled: 24, last: 23, no_scrolling: 0
NOT updating rest of lines; row = 24 end = 23 fp = 1 ip = 0
update_window NOT preempted
redisplay_preserve_echo_area (8)
redisplay_internal 0
update_window: first enabled: 24, last: 23, no_scrolling: 0
NOT updating rest of lines; row = 24 end = 23 fp = 1 ip = 0
update_window NOT preempted
redisplay_preserve_echo_area (8)
redisplay_internal 0
update_window: first enabled: 24, last: 23, no_scrolling: 0
NOT updating rest of lines; row = 24 end = 23 fp = 1 ip = 0
update_window NOT preempted
redisplay_preserve_echo_area (8)
redisplay_internal 0
update_window: first enabled: 24, last: 23, no_scrolling: 0
NOT updating rest of lines; row = 24 end = 23 fp = 1 ip = 0
update_window NOT preempted
redisplay_preserve_echo_area (8)
redisplay_internal 0
update_window: first enabled: 24, last: 23, no_scrolling: 0
NOT updating rest of lines; row = 24 end = 23 fp = 1 ip = 0
update_window NOT preempted
redisplay_preserve_echo_area (8)
redisplay_internal 0
update_window: first enabled: 24, last: 23, no_scrolling: 0
NOT updating rest of lines; row = 24 end = 23 fp = 1 ip = 0
update_window NOT preempted
redisplay_preserve_echo_area (8)
redisplay_internal 0
update_window: first enabled: 24, last: 23, no_scrolling: 0
NOT updating rest of lines; row = 24 end = 23 fp = 1 ip = 0
update_window NOT preempted
redisplay_internal 0
0x3201120 (*Group*): same window start
0x3201120 (*Group*): 1
update_window: first enabled: 0, last: 88, no_scrolling: 0
scrolling_window found all rows equal
update_window: first enabled: 0, last: 3, no_scrolling: 0
clear_frame_area: [9 - 569] [1132 - 1145]
update_window marks rows 1 - 3 invalid
update_window NOT preempted
0x117b8d0 (*Summary nntp+news.gmane.org:gwene.com.wordpress.arnoldzwicky*): same window start
0x117b8d0 (*Summary nntp+news.gmane.org:gwene.com.wordpress.arnoldzwicky*): 1
0x3b5ada8 (*Article nntp+news.gmane.org:gwene.com.wordpress.arnoldzwicky*): same window start
0x3b5ada8 (*Article nntp+news.gmane.org:gwene.com.wordpress.arnoldzwicky*): 1
0x117c8e0 ( *Minibuf-1*): same window start
0x117c8e0 ( *Minibuf-1*): 1
update_window: first enabled: 0, last: 23, no_scrolling: 0
scrolling_window found all rows equal
update_window: first enabled: 0, last: 67, no_scrolling: 0
update_window marks rows 65 - 67 invalid
update_window NOT preempted
update_window: first enabled: 0, last: 3, no_scrolling: 0
clear_frame_area: [58 - 569] [1145 - 1158]
update_window marks rows 1 - 3 invalid
update_window NOT preempted
redisplay_internal 0
0x117c8e0 ( *Minibuf-1*): same window start
0x117c8e0 ( *Minibuf-1*): 1
update_window: first enabled: 0, last: 3, no_scrolling: 0
clear_frame_area: [205 - 569] [1145 - 1158]
update_window marks rows 1 - 3 invalid
update_window NOT preempted
redisplay_preserve_echo_area (8)
redisplay_internal 0
trying display optimization 1
0x117c8e0 ( *Minibuf-1*): optimization 1
update_window: first enabled: 0, last: 3, no_scrolling: 1
update_window marks rows 1 - 3 invalid
update_window NOT preempted
update_window: first enabled: 4, last: 3, no_scrolling: 0
NOT updating rest of lines; row = 4 end = 3 fp = 1 ip = 0
update_window NOT preempted
PT = 10, BEGV = 1. ZV = 62
Cursor x = 63, y = 0, hpos = 9, vpos = 0
=============================================
Row     Start       End Used oE><\CTZFesm     X    Y    W    H    V    A    P
==============================================================================
  0         1        62   61 010000100000     0    0  427   13   13   11   11
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      0     C         1   B   7 0x000021      !   15 00
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      2     C         3   B   7 0x000020          15 00
      3     C         4   B   7 0x00005b      [   16 00
      4     C         5   B   7 0x000020          16 00
      5     C         6   B   7 0x000020          16 00
      6     C         7   B   7 0x000031      1   16 00
      7     C         8   B   7 0x000035      5   16 00
      8     C         9   B   7 0x00003a      :   16 00
      9     C        10   B   7 0x000020          16 00
     10     C        11   B   7 0x000061      a   16 00
     11     C        12   B   7 0x000072      r   16 00
     12     C        13   B   7 0x00006e      n   16 00
     13     C        14   B   7 0x00006f      o   16 00
     14     C        15   B   7 0x00006c      l   16 00
     15     C        16   B   7 0x000064      d   16 00
     16     C        17   B   7 0x000020          16 00
     17     C        18   B   7 0x00007a      z   16 00
     18     C        19   B   7 0x000077      w   16 00
     19     C        20   B   7 0x000069      i   16 00
     20     C        21   B   7 0x000063      c   16 00
     21     C        22   B   7 0x00006b      k   16 00
     22     C        23   B   7 0x000079      y   16 00
     23     C        24   B   7 0x000020          16 00
     24     C        25   B   7 0x000020          16 00
     25     C        26   B   7 0x000020          16 00
     26     C        27   B   7 0x000020          16 00
     27     C        28   B   7 0x000020          16 00
     28     C        29   B   7 0x000020          16 00
     29     C        30   B   7 0x000020          16 00
     30     C        31   B   7 0x000020          16 00
     31     C        32   B   7 0x000020          16 00
     32     C        33   B   7 0x000020          16 00
     33     C        34   B   7 0x00005d      ]   16 00
     34     C        35   B   7 0x000020          15 00
     35     C        36   B   7 0x000041      A   15 00
     36     C        37   B   7 0x000075      u   15 00
     37     C        38   B   7 0x000073      s   15 00
     38     C        39   B   7 0x000074      t   15 00
     39     C        40   B   7 0x000065      e   15 00
     40     C        41   B   7 0x00006e      n   15 00
     41     C        42   B   7 0x000069      i   15 00
     42     C        43   B   7 0x000061      a   15 00
     43     C        44   B   7 0x00006e      n   15 00
     44     C        45   B   7 0x000020          15 00
     45     C        46   B   7 0x000068      h   15 00
     46     C        47   B   7 0x000075      u   15 00
     47     C        48   B   7 0x00006d      m   15 00
     48     C        49   B   7 0x000062      b   15 00
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     50     C        51   B   7 0x000065      e   15 00
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     58     C        59   B   7 0x000067      g   15 00
     59     C        60   B   7 0x00003f      ?   15 00
     60     C         0   0   7 0x000020           0 00
Row     Start       End Used oE><\CTZFesm     X    Y    W    H    V    A    P
==============================================================================
  1        62        62    1 010000010000     0   13    7   13   13   11    0
           -1        -1	    0
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 Glyph#  Type       Pos   O   W     Code      C Face LR
      0     C        -1   0   7 0x000020           0 00
Row     Start       End Used oE><\CTZFesm     X    Y    W    H    V    A    P
==============================================================================
  2        62        62    1 010000010000     0   26    7   13   13   11    0
           -1        -1	    0
           -1        -1
           -1        -1
 Glyph#  Type       Pos   O   W     Code      C Face LR
      0     C        -1   0   7 0x000020           0 00
Row     Start       End Used oE><\CTZFesm     X    Y    W    H    V    A    P
==============================================================================
  3        62        62    1 010000010000     0   39    7   13   13   11    0
           -1        -1	    0
           -1        -1
           -1        -1
 Glyph#  Type       Pos   O   W     Code      C Face LR
      0     C        -1   0   7 0x000020           0 00
Row     Start       End Used oE><\CTZFesm     X    Y    W    H    V    A    P
==============================================================================
  4        62        62    1 010000010000     0   52    7   13   13   11    0
           -1        -1	    0
           -1        -1
           -1        -1
 Glyph#  Type       Pos   O   W     Code      C Face LR
      0     C        -1   0   7 0x000020           0 00
Row     Start       End Used oE><\CTZFesm     X    Y    W    H    V    A    P
==============================================================================
  5        62        62    1 010000010000     0   65    7   13   13   11    0
           -1        -1	    0
           -1        -1
           -1        -1
 Glyph#  Type       Pos   O   W     Code      C Face LR
      0     C        -1   0   7 0x000020           0 00
Row     Start       End Used oE><\CTZFesm     X    Y    W    H    V    A    P
==============================================================================
  6        62        62    1 010000010000     0   78    7   13   13   11    0
           -1        -1	    0
           -1        -1
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 Glyph#  Type       Pos   O   W     Code      C Face LR
      0     C        -1   0   7 0x000020           0 00
Row     Start       End Used oE><\CTZFesm     X    Y    W    H    V    A    P
==============================================================================
  7        62        62    1 010000010000     0   91    7   13   13   11    0
           -1        -1	    0
           -1        -1
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 Glyph#  Type       Pos   O   W     Code      C Face LR
      0     C        -1   0   7 0x000020           0 00
Row     Start       End Used oE><\CTZFesm     X    Y    W    H    V    A    P
==============================================================================
  8        62        62    1 010000010000     0  104    7   13   13   11    0
           -1        -1	    0
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 Glyph#  Type       Pos   O   W     Code      C Face LR
      0     C        -1   0   7 0x000020           0 00
Row     Start       End Used oE><\CTZFesm     X    Y    W    H    V    A    P
==============================================================================
  9        62        62    1 010000010000     0  117    7   13   13   11    0
           -1        -1	    0
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 Glyph#  Type       Pos   O   W     Code      C Face LR
      0     C        -1   0   7 0x000020           0 00
Row     Start       End Used oE><\CTZFesm     X    Y    W    H    V    A    P
==============================================================================
 10        62        62    1 010000010000     0  130    7   13   13   11    0
           -1        -1	    0
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 Glyph#  Type       Pos   O   W     Code      C Face LR
      0     C        -1   0   7 0x000020           0 00
Row     Start       End Used oE><\CTZFesm     X    Y    W    H    V    A    P
==============================================================================
 11        62        62    1 010000010000     0  143    7   13   13   11    0
           -1        -1	    0
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           -1        -1
 Glyph#  Type       Pos   O   W     Code      C Face LR
      0     C        -1   0   7 0x000020           0 00
Row     Start       End Used oE><\CTZFesm     X    Y    W    H    V    A    P
==============================================================================
 12        62        62    1 010000010000     0  156    7   13   13   11    0
           -1        -1	    0
           -1        -1
           -1        -1
 Glyph#  Type       Pos   O   W     Code      C Face LR
      0     C        -1   0   7 0x000020           0 00
Row     Start       End Used oE><\CTZFesm     X    Y    W    H    V    A    P
==============================================================================
 13        62        62    1 010000010000     0  169    7   13   13   11    0
           -1        -1	    0
           -1        -1
           -1        -1
 Glyph#  Type       Pos   O   W     Code      C Face LR
      0     C        -1   0   7 0x000020           0 00
Row     Start       End Used oE><\CTZFesm     X    Y    W    H    V    A    P
==============================================================================
 14        62        62    1 010000010000     0  182    7   13   13   11    0
           -1        -1	    0
           -1        -1
           -1        -1
 Glyph#  Type       Pos   O   W     Code      C Face LR
      0     C        -1   0   7 0x000020           0 00
Row     Start       End Used oE><\CTZFesm     X    Y    W    H    V    A    P
==============================================================================
 15        62        62    1 010000010000     0  195    7   13   13   11    0
           -1        -1	    0
           -1        -1
           -1        -1
 Glyph#  Type       Pos   O   W     Code      C Face LR
      0     C        -1   0   7 0x000020           0 00
Row     Start       End Used oE><\CTZFesm     X    Y    W    H    V    A    P
==============================================================================
 16        62        62    1 010000010000     0  208    7   13   13   11    0
           -1        -1	    0
           -1        -1
           -1        -1
 Glyph#  Type       Pos   O   W     Code      C Face LR
      0     C        -1   0   7 0x000020           0 00
Row     Start       End Used oE><\CTZFesm     X    Y    W    H    V    A    P
==============================================================================
 17        62        62    1 010000010000     0  221    7   13   13   11    0
           -1        -1	    0
           -1        -1
           -1        -1
 Glyph#  Type       Pos   O   W     Code      C Face LR
      0     C        -1   0   7 0x000020           0 00
Row     Start       End Used oE><\CTZFesm     X    Y    W    H    V    A    P
==============================================================================
 18        62        62    1 010000010000     0  234    7   13   13   11    0
           -1        -1	    0
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 Glyph#  Type       Pos   O   W     Code      C Face LR
      0     C        -1   0   7 0x000020           0 00
Row     Start       End Used oE><\CTZFesm     X    Y    W    H    V    A    P
==============================================================================
 19        62        62    1 010000010000     0  247    7   13   13   11    0
           -1        -1	    0
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 Glyph#  Type       Pos   O   W     Code      C Face LR
      0     C        -1   0   7 0x000020           0 00
Row     Start       End Used oE><\CTZFesm     X    Y    W    H    V    A    P
==============================================================================
 20        62        62    1 010000010000     0  260    7   13   13   11    0
           -1        -1	    0
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 Glyph#  Type       Pos   O   W     Code      C Face LR
      0     C        -1   0   7 0x000020           0 00
Row     Start       End Used oE><\CTZFesm     X    Y    W    H    V    A    P
==============================================================================
 21        62        62    1 000000010000     0  273    7   13   13   11    0
           -1        -1	    0
           -1        -1
           -1        -1
 Glyph#  Type       Pos   O   W     Code      C Face LR
      0     C        -1   0   7 0x000020           0 00
Row     Start       End Used oE><\CTZFesm     X    Y    W    H    V    A    P
==============================================================================
 22        62        62    1 000000010000     0  286    7   13   13   11    0
           -1        -1	    0
           -1        -1
           -1        -1
 Glyph#  Type       Pos   O   W     Code      C Face LR
      0     C        -1   0   7 0x000020           0 00
Row     Start       End Used oE><\CTZFesm     X    Y    W    H    V    A    P
==============================================================================
 23        62        62    1 000000010000     0  299    7   13   13   11    0
           -1        -1	    0
           -1        -1
           -1        -1
 Glyph#  Type       Pos   O   W     Code      C Face LR
      0     C        -1   0   7 0x000020           0 00
Row     Start       End Used oE><\CTZFesm     X    Y    W    H    V    A    P
==============================================================================
 24         0         0   81 010000000000     0  273  579   13   13   11   11
            0         0	    0
            0         0
            0         0
 Glyph#  Type       Pos   O   W     Code      C Face LR
      0     C         0   S   8 0x000020           1 10
      1     C         1   S   7 0x000031      1    1 00
      2     C         0   S   7 0x00003a      :    1 00
      3     C         0   S   7 0x00002d      -    1 00
      4     C         1   S   7 0x00002d      -    1 00
      5     C         1   S   7 0x00002d      -    1 00
      6     C         0   S   7 0x000020           1 00
      7     C         1   S   7 0x000020           1 00
      8     I         0   S  18 0x000001      .    1 00
      9     C         5   S   7 0x000020           1 00
     10     C         6   S   7 0x00006e      n    1 00
     11     C         7   S   7 0x000065      e    1 00
     12     C         8   S   7 0x000077      w    1 00
     13     C         9   S   7 0x000073      s    1 00
     14     C        10   S   7 0x00003a      :    1 00
     15     C        11   S   7 0x000067      g    1 00
     16     C        12   S   7 0x00002e      .    1 00
     17     C        13   S   7 0x000063      c    1 00
     18     C        14   S   7 0x00002e      .    1 00
     19     C        15   S   7 0x000077      w    1 00
     20     C        16   S   7 0x00002e      .    1 00
     21     C        17   S   7 0x000061      a    1 00
     22     C        18   S   7 0x000072      r    1 00
     23     C        19   S   7 0x00006e      n    1 00
     24     C        20   S   7 0x00006f      o    1 00
     25     C        21   S   7 0x00006c      l    1 00
     26     C        22   S   7 0x000064      d    1 00
     27     C        23   S   7 0x00007a      z    1 00
     28     C        24   S   7 0x000077      w    1 00
     29     C        25   S   7 0x000069      i    1 00
     30     C        26   S   7 0x000063      c    1 00
     31     C        27   S   7 0x00006b      k    1 00
     32     C        28   S   7 0x000079      y    1 00
     33     C        29   S   7 0x000020           1 00
     34     C        30   S   7 0x00005b      [    1 00
     35     C        31   S   7 0x000033      3    1 00
     36     C        32   S   7 0x000034      4    1 00
     37     C        33   S   7 0x000030      0    1 00
     38     C        34   S   7 0x000031      1    1 00
     39     C        35   S   7 0x00005d      ]    1 00
     40     C        36   S   7 0x000020           1 00
     41     C         0   S   7 0x000020           1 00
     42     C         1   S   7 0x000020           1 00
     43     C         2   S   7 0x000020           1 00
     44     C         1   S   7 0x000041      A    1 00
     45     C         1   S   7 0x00006c      l    1 00
     46     C         1   S   7 0x00006c      l    1 00
     47     C         0   S   7 0x000020           1 00
     48     C         1   S   7 0x00004c      L    1 00
     49     C         3   S   7 0x000031      1    1 00
     50     C        -1   -   7 0x000020           1 00
     51     C        -1   -   7 0x000020           1 00
     52     C        -1   -   7 0x000020           1 00
     53     C         0   S   7 0x000020           1 00
     54     C         1   S   7 0x000020           1 00
     55     C         0   S   7 0x000028      (    1 00
     56     C         0   S   7 0x000053      S    1 00
     57     C         1   S   7 0x000075      u    1 00
     58     C         2   S   7 0x00006d      m    1 00
     59     C         3   S   7 0x00006d      m    1 00
     60     C         4   S   7 0x000061      a    1 00
     61     C         5   S   7 0x000072      r    1 00
     62     C         6   S   7 0x000079      y    1 00
     63     C         0   S   7 0x000020           1 00
     64     C         1   S   7 0x000050      P    1 00
     65     C         2   S   7 0x00006c      l    1 00
     66     C         3   S   7 0x000075      u    1 00
     67     C         4   S   7 0x000067      g    1 00
     68     C         5   S   7 0x000067      g    1 00
     69     C         6   S   7 0x000065      e    1 00
     70     C         7   S   7 0x000064      d    1 00
     71     C         0   S   7 0x000029      )    1 00
     72     C         0   S   7 0x000020           1 00
     73     C         0   -   7 0x000020           1 00
     74     C        -1   -   7 0x000020           1 00
     75     C        -1   -   7 0x000020           1 00
     76     C        -1   -   7 0x000020           1 00
     77     C        -1   -   7 0x000020           1 00
     78     C        -1   -   7 0x000020           1 00
     79     C        -1   -   7 0x000020           1 00
     80     C        -1   -   7 0x000020           1 01
redisplay_internal 0
0x3201120 (*Group*): same window start
0x3201120 (*Group*): 1
update_window: first enabled: 0, last: 88, no_scrolling: 0
scrolling_window found all rows equal
update_window: first enabled: 0, last: 3, no_scrolling: 0
scrolling_window found all rows equal
0x117b8d0 (*Summary nntp+news.gmane.org:gwene.com.wordpress.arnoldzwicky*): same window start
0x117b8d0 (*Summary nntp+news.gmane.org:gwene.com.wordpress.arnoldzwicky*): 1
0x3b5ada8 (*Article nntp+news.gmane.org:gwene.com.wordpress.arnoldzwicky*): same window start
0x3b5ada8 (*Article nntp+news.gmane.org:gwene.com.wordpress.arnoldzwicky*): 1
update_window: first enabled: 0, last: 23, no_scrolling: 0
scrolling_window found all rows equal
update_window: first enabled: 0, last: 67, no_scrolling: 0
update_window marks rows 65 - 67 invalid
update_window NOT preempted
update_window: first enabled: 0, last: 3, no_scrolling: 0
clear_frame_area: [37 - 569] [1145 - 1158]
update_window marks rows 1 - 3 invalid
update_window NOT preempted
redisplay_preserve_echo_area (8)
redisplay_internal 0
update_window: first enabled: 24, last: 23, no_scrolling: 0
NOT updating rest of lines; row = 24 end = 23 fp = 1 ip = 0
update_window NOT preempted
update_window: first enabled: 0, last: 3, no_scrolling: 0
scrolling_window found all rows equal
redisplay_internal 0
update_window: first enabled: 24, last: 23, no_scrolling: 0
NOT updating rest of lines; row = 24 end = 23 fp = 1 ip = 0
update_window NOT preempted
update_window: first enabled: 0, last: 3, no_scrolling: 0
scrolling_window found all rows equal
redisplay_preserve_echo_area (8)
redisplay_internal 0
update_window: first enabled: 24, last: 23, no_scrolling: 0
NOT updating rest of lines; row = 24 end = 23 fp = 1 ip = 0
update_window NOT preempted
update_window: first enabled: 0, last: 3, no_scrolling: 0
scrolling_window found all rows equal
redisplay_internal 0
update_window: first enabled: 24, last: 23, no_scrolling: 0
NOT updating rest of lines; row = 24 end = 23 fp = 1 ip = 0
update_window NOT preempted
update_window: first enabled: 0, last: 3, no_scrolling: 0
scrolling_window found all rows equal
redisplay_preserve_echo_area (8)
redisplay_internal 0
update_window: first enabled: 24, last: 23, no_scrolling: 0
NOT updating rest of lines; row = 24 end = 23 fp = 1 ip = 0
update_window NOT preempted
update_window: first enabled: 0, last: 3, no_scrolling: 0
scrolling_window found all rows equal
redisplay_internal 0
update_window: first enabled: 24, last: 23, no_scrolling: 0
NOT updating rest of lines; row = 24 end = 23 fp = 1 ip = 0
update_window NOT preempted
update_window: first enabled: 0, last: 3, no_scrolling: 0
scrolling_window found all rows equal
redisplay_internal 0
update_window: first enabled: 24, last: 23, no_scrolling: 0
NOT updating rest of lines; row = 24 end = 23 fp = 1 ip = 0
update_window NOT preempted
update_window: first enabled: 0, last: 3, no_scrolling: 0
scrolling_window found all rows equal
redisplay_preserve_echo_area (8)
redisplay_internal 0
update_window: first enabled: 24, last: 23, no_scrolling: 0
NOT updating rest of lines; row = 24 end = 23 fp = 1 ip = 0
update_window NOT preempted
update_window: first enabled: 0, last: 3, no_scrolling: 0
scrolling_window found all rows equal

Then I've scrolled the article back up again, so we get the same display
as in the first image.

And now for the buggy display.  I've scrolled the article down again,
and we see lots of the remaining image from the pre-scrolled buffer, and
text is also missing, if you compare with the second image.

Hopefully I've matched up the right parts here now.

And thanks again for looking into this.  This type of bug is pretty
tedious to chase down.

I've shrunken the images somewhat this time, and converted to .jpg, to
avoid a very large mail.

-- 
(domestic pets only, the antidote for overdose, milk.)
   bloggy blog: http://lars.ingebrigtsen.no