Change gdm3 login background

[pwzhangzz]

I edited the /etc/gdm3/greeter.dconf-defaults file to try to change the gdm3 login background by changing the picture-uri paramater:

# picture-uri='file:///usr/share/themes/Adwaita/backgrounds/stripes.jpg'
picture-uri='file:///usr/share/images/vendor-logos/Emerald_login_1920x1080.svg'

This has no effect. Then I changed the logo parameter:

#logo='/usr/share/images/vendor-logos/logo-text-version-64.png'
logo='/usr/share/images/vendor-logos/Emerald_login_1920x1080.svg'

This step changed the login "background". But what was intended to be background became foreground blocking the user list and the password prompt. The second observation, of course, should be expected as a logo would appear in the foreground. But how to change the background of a gdm3 login screen?

? ? ?

[pwzhangzz]

The following screenshot shows that I was able to use Juliette's emerald svg as my gdm3 login screen (& it looks really good!):

However, I had to use a flatpak called "Login Manager Settings"* to do the change. Not to diminish the hard efforts by this great flatpak's author, but I would like to stay within the Debian apt system. Things should be much simpler for just changing the login screen? ? ?

* https://flathub.org/apps/details/io.git ... dmSettings