Created attachment 8371 0001-Add-support-for-elogind.patch elogind is a stand-alone replacement for systemd's logind. It provides compatible D-Bus interface but different library names. Please consider supporting it as an alternative to systemd-logind. I'm attaching a patch implementing this support.
Michał Górny referenced this bugreport in commit 7faa39544c7fbafb39daa55382d30be31a1a6950 Add support for elogind (bug #15243) https://git.xfce.org/apps/xfce4-screensaver/commit?id=7faa39544c7fbafb39daa55382d30be31a1a6950
Due to recent changes, I also had to apply a patch here: https://git.xfce.org/apps/xfce4-screensaver/commit/?id=b30dece8bde7845137d6f0e60495c62d18668377 Please test this and let me know if any other changes are needed. Thanks!