I am trying to figure out where the “default avatar icon” is coming from when “disable-user-name” is set to ‘true’ and the GDM Face Browser is turned off, see screen shot:
Gnome help docs say:
If a user has no defined face image, GDM will use the "stock_person" icon defined in the current GTK+ theme. If no such image is defined, it will fallback to a generic face image.
but i was unable to find that ‘stock_person’ icon, nor that ‘generic face image’ on my system (and believe me, i tried). Also i doubt the info in Gnome help above is still true.
I remember ‘the good ol’ days’ when you just logged in as user ‘gdm’ and set that icon to what ever you liked. But since the make-over of GDM (or Simple Greeter? or GDMlogin?) there is no gdm user to login to, and gresources took over for a part.
This icon is not reachable via dconf settings. ‘Greeter Logo’ is a logo at the bottom of the screen. .face files and so do not work anymore. Maybe an inline SVG?