Thanks for the feedback. I’m really not an expert and hoped sharing my fix would result in either validation or constructive criticism. Xapp sounded like a good default for XFCE, its description says “A backend implementation for xdg-desktop-portal using GTK and various pieces of Cinnamon/MATE/Xfce4 infrastructure”. My understanding is, GTK is the fallback anyway? Should be ok, no?
I got GNOME on my notebook. That install didn’t have the issue discussed here, so I used its setup to reverse engineer the portal conf and backends. The GNOME portal conf uses “default=gnome;gtk;”, so I just followed that example and replaced gnome with xapp for the XFCE install.
I looked through the github of xapp and it seems to do very little for XFCE. I tried xapp as the mere default and everything broke again, then I set GTK as mere default and everything worked as intended. I’m going to revise my fix up thread.
Thank you @Yochanan , the solution is still valid and the extra information I brought can also be useful to other people facing the same problem. It’s indeed more useful here than in a separate extra topic
It’s good to have this fixes at hand, but maybe something should be done to negate the need for a manual fix in the first place.
I’m also using a GNOME install, it got the correct portal conf /usr/share/xdg-desktop-portal/portals/gnome.portal … although I have no idea, which package placed it there. I only recently setup a new notebook and definitely didn’t have to do this manually. It just worked out of the box.
Maybe it would be a good idea to have a xdg-desktop-portal-xfce package for XFCE to setup the required portal conf, environment variable and a dependency on xdg-desktop-portal-gtk?