New tests: GTK3 platform accessibility

[Stephan Bergmann]

On 8/25/23 09:06, Michael Weghorn wrote:
> In my test, it failed differently on Wayland, and forcing the X11 Gdk 
> backend makes that work:
> https://gerrit.libreoffice.org/c/core/+/156086
> 
> Does that fix your case as well?

no

> Otherwise: Does the test work when run in an X11 session instead?

no; guess I need to install some piece of software that is missing from 
my machine