bug#38016: 27.0.50; Display issues with delay-warning and side-by-side windows in terminal

[Tom Levy <tomlevy93@gmail.com>]

Thanks for taking a look. The lines don't really change, "M-x
redraw-display RET" returns the display to the expected state.*

It happens for me on Debian 9.11 and 10 (in a clean VM), should I try
another OS?


* Just pressing "M-x" changes the display. With the first variation
(i.e. ... C-e RET DEL M-x) it returns the display to the expected state.
With the second variation (i.e. ... C-e a RET M-x) it correctly displays
"line 2" on the second line, but doesn't clear the third line; when I
continue with "redraw-display RET" the third line is cleared, returning
the display to the expected state.

On Fri, 1 Nov 2019 at 20:06, Eli Zaretskii <eliz@gnu.org> wrote:
>
> > From: Tom Levy <tomlevy93@gmail.com>
> > Date: Fri, 01 Nov 2019 18:11:45 +1300
> >
> > Maximize a terminal window to make Emacs use a side-by-side window split.
> > Run: emacs -Q -nw --eval '(delay-warning :debug "line 1\nline 2")'
> > The *scratch* and *Warnings* buffers should be displayed side by side.
> > Press M-< C-e RET DEL (in the *scratch* buffer).
> > Line 2 in the *Warnings* buffer disappears (!)
> >
> > Variation: run Emacs as before, but press M-< C-e a RET
> > Line 2 in the *Warnings* buffer moves down (!)
> >
> > Happens in master (27.0.50) and 24.5.1, with both gnome-terminal and
> > xterm.
>
> I couldn't reproduce this, neither on GNU/Linux nor on MS-Windows.
> Can anyone else reproduce this?
>
> Does the "disappearing" and "moving" text really disappear and move?
> What happens if you invoke "M-x redraw-display RET" after your recipe:
> does the display return to be as expected?