[Bug: 21.5-b28] unusability of VM under 21.5

[Julian Bradfield]

In article <y9lhcm7hoan.fsf at informatik.uni-tuebingen.de> Michael Sperber <sperber at informatik.uni-tuebingen.de> writes:
>
>Marcus Harnisch <marcus.harnisch at gmx.net> writes:
>> [...]
>> enter a folder with (> (frame-height)) messages
>>
>> C-x 1       ; see more of the summary
>>
>> move point to a message far down in the summary
>>
>> SPACE       ; display message
>>
>> watch how summary window shrinks to make space for message body. The
>> message number at the top of the summary window is the same as
>> before. point is re-centered in current (shrunk) summary window.
>
>Huh.  I tried this on a folder with >1000 messages.  Response is
>instantaneous, but I do see the point move.  I'll look into that.  Are
>you also complaining that it's very slow for you, or is it just the
>point move?

Marcus' example demonstrates the unwanted movement of point, but not
the flickering. For the latter, do the following:

prepare a folder with (at least) two messages, one being a plain text
message, the other, immediately following, being a MIME message
(e.g. multipart/alternative). 
Select the plain text message in the summary (with SP). It displays
cleanly. Now do "n" to move to the MIME message. You (or at least I)
see the window config flicker as VM decodes the message, in a way that
doesn't happen under 21.4
The flicker seems especially noticeable on something with, say, a big
PDF attachment that will have a button in the presentation buffer.