Subject: bug#76703: Emacs running in Terminal does not change the background color of the bottom right corner

From: Codruț Constantin Gușoi <[email-masked]>
Date: Sun, 02 Mar 2025 15:51:52 +0000

Hello,

This has been a thing that I've noticed in Emacs since I started using 
it a decade ago, but I kind of ignored it. I'd like to see a proper fix 
for it though.

Running any Emacs version (tested on 29.4 and 31.0.50 from 2nd of March 
2025 commit c4232a08f135b347a24cb75bb901659d45c61787) in a terminal 
makes the bottom right corner not respect a theme's background colour.

You have screenshots in this snippet: 
https://gitlab.com/-/snippets/4814843, also attached.

Exhibit 1 - Emacs running with the following command:

```

|emacs -Q -nw --eval '(dolist (face (face-list)) (set-face-foreground 
face "white") (set-face-background face "white"))' |

```

Notice the bottom right corner is dark, same colour as the terminal 
background.

Exhibit 2 - vim running with the following command:

```

vim -u NONE -c "colorscheme delek"

```

Notice the bottom right corner is white, same colour as the theme.

Now, because vim can do it, it means it's not impossible, and Emacs can 
also implement something similar and fix this issue. It's kind of hard 
for me to figure out what is going on here. From what I've understood 
this has something to do with the way Emacs handles cursors?