bug#12906: 24.2.50; Parts of the screen are completely white

[Fabrice Niessen]

Elli,

"Fabrice Niessen" wrote:
> Eli Zaretskii wrote:
>>> From: "Fabrice Niessen" <fni@missioncriticalit.com>
>>>
>>> I sometimes have parts of the screen "undisplayed" such in the
>>> example at http://screencast.com/t/qLMxmSLxYvJ8.
>>> 
>>> In the beginning, all the line was white (even the fringe!).
>>> 
>>> While moving the cursor around, some characters are redisplayed correctly.
>>> 
>>> Paging up and down makes the display correct again.
>>
>> This is a clear sign that some redisplay optimization is applied when
>> it shouldn't be.  IOW, Emacs mistakenly thinks the display does not
>> need to be redrawn.
>>
>>> However, this is not occurring often, and not reproducible per se -- 
>>> unluckily.
>>
>> When that happens next, try typing "M-x".  Just "M-x", without any
>> command.
>
> That did not help, in the Org buffer I was just looking at...
>
>> If that doesn't help, try "M-x redraw-display RET".
>
> That did work -- in fact, before applying it!  Why?  Because I typed M-x red
> TAB, and a buffer came on the right side of my screen, full with completions.
> When that one appeared, the display was corrected.
>
>> More importantly, post the result of "C-h l" (that's ell, not the
>> digit one), and try to remember what were you doing immediately before
>> the incident.  Also, in what mode was the current buffer.
>
> Just browsing the file with C-v/M-v.
>
> I'm sorry, but, by answering to this email first, I'd lost what you wanted
> from C-h l.

This time, I could write redraw-display without TAB'ing. It did redraw the
screen correctly.

And here the lossage view you asked for:

--8<---------------cut here---------------start------------->8---
SPC SPC SPC SPC SPC SPC <down> <down> <down> <down>
<down> <down> <down> <down> <down> <down> <down> <down>
<down> <down> <down> <down> <down> <down> <down> <down>
<down> <down> <down> <down> <down> <down> <down> <down>
<down> <down> <down> <down> <down> <down> <down> <down>
<down> <down> <down> <down> <down> <down> <down> <down>
<down> <down> <up> <up> <up> <up> <up> <up> <up> <up>
<up> <left> C-a C-c C-v C-d <down> <down> <down> <down>
<down> <down> <down> <down> <down> <down> <down> <down>
<down> <up> <up> <up> <up> <up> <up> <up> <up> <up>
<up> <up> <up> <up> <up> <up> <up> <up> <up> <up> <up>
<up> <up> <up> <up> C-c C-v C-d <down> <down> <down>
<down> <down> <down> <down> <down> <down> <down> <down>
<down> <down> <down> <down> <down> <down> <down> <down>
<down> <down> <down> <down> <down> <down> <down> <down>
<down> <down> <down> <down> <down> <down> <down> <down>
<down> <down> <down> <down> <down> <down> <down> <down>
<down> <down> <down> <down> <down> C-x C-s <up> <up>
<up> <up> <up> <up> <up> <up> <up> <up> <up> <up> <up>
<up> <up> <up> <up> <up> <up> <up> <up> <up> <up> <up>
<up> <up> <up> <up> <up> <up> <up> <up> <up> <up> <up>
<up> <up> <up> <up> <up> <up> <up> <up> <up> <up> <up>
<up> <up> <up> <up> <up> <up> <up> <up> <up> <up> <up>
<up> <up> <up> <up> <up> <up> <up> <up> <up> <up> <up>
<up> <up> <up> <up> <up> <up> <up> <up> <up> <up> <up>
<up> <up> <up> <up> <up> <up> <up> <up> <up> <up> <up>
<up> <up> <up> <up> <up> <up> <up> <up> <up> <up> <up>
<up> <up> <up> <up> <up> <up> <up> <up> <up> <up> <up>
<up> <up> <up> <up> <up> <up> <up> <up> <up> <up> <up>
M-x <up> r e d r a w - d s <backspace> i s p l a y
<return> C-h l

[back]
--8<---------------cut here---------------end--------------->8---

On the big Org file (13,000 lines, 454 KB) I'm working on, the problem is
pretty reproducible...

Best regards,
Fabrice