bug#57728: 29.0.50; Emacs writes wrong glyph at the bottom-right corner of text terminals

[Gerd Möllmann]

Gregory Heytings <gregory@heytings.org> writes:

> Here is (I think) a recipe to demonstrate what the OP has in mind
> (tested with xterm, rxvt, st, kitty, alacritty, Linux console):
>
> 1. emacs -Q -nw
>
> 2a. if your terminal emulator has a light background: M-x load-theme
> RET modus-vivendi RET
>
> 2b. if your terminal emulator has a dark background: M-x load-theme
> RET modus-operandi RET
>
> Observe at that point that the last character (the one at the bottom
> right) does not have the background color of the chosen theme.  So far
> so good.

The OP filed a bug for this, and he might work on it he said.

This is because 'write' deliberatly leaves the bottom-right corner alone
if the terminal has "auto right margin" (autowrap).