I'm using Xubuntu 20.04. lightdm-gtk-greeter-settings version 1.2.2-3 is installed.
Open lightdm-gtk-greeter-settings
Select radio button to get an "Image" background
Click the image chooser "button"
In my distribution, the FileChooser opens in the /usr/share/backgrounds directory
The FileChooser does not display the image thumbnails. This is not very convenient to select an image. I'm almost sure I saw image thumbnails in other Gtk FileChoosers (e.g. in gimp, but there it might be their own dialogbox?).
What's worse is that this Gtk FileChooser does not allow to copy the current path (CTRL-L opens an emptyeditor line), thus one cannot easily copy the "/usr/share/backgrounds" path in an image viewer application (see bug report here: https://gitlab.gnome.org/GNOME/gtk/-/issues/2443)
Reported first on Launchpad at https://bugs.launchpad.net/lightdm-gtk-greeter-settings/+bug/1882961
LP#0: G.M. (sexxxenator) wrote on 2020-06-10: