Subject: bug#11099: 23.2; Filter function causes flickering in minibuffer

From: Lars Ingebrigtsen <[email-masked]>
Date: Sat, 17 Aug 2019 16:25:55 -0700

Sean McLaughlin <[email-masked]> writes:

> 1) Create a file count.sh
>
> #!/bin/bash
>
> ctr=0
>
> while true; do
>     sleep 1
>     echo "ctr = $ctr"
>     ctr=$(( ctr + 1 ))
> done
>
> 2) Create a buffer called *count*
>
> 3) Start count asyncronously from a clean emacs (-q)
>
> (defun Tmp.filter-fun (proc s)
>   (with-current-buffer "*count*"
>     (insert s)))
>
> (defun Tmp.count ()
>   (interactive)
>   (let ((process
>          (start-process
>           "count"
>           "*count*"
>           "/home/seanmcl/bin/count")))
>     (set-process-filter process 'Tmp.filter-fun)))
>
> 4) Type C-x
>
> This will cause C-x to show up in the minibuffer.  Every time a
> line is filtered from count, the C-x flickers in the minibuffer,
> sometimes moving a character to the right and then back to the
> left.

(I'm going through old bug reports that unfortunately have gotten no
responses yet.)

It looks like this has been fixed in the intervening years -- now you
won't get a "C-x" in the echo area because it's not displayed when
filters are running, apparently.

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