Thanks! Suddenly X11:XOrg/libX11 and openSUSE:Factory/libX11 are back 1.8.1. No idea how. Looks like the downgrade was reverted somewhow. Sorry, this is too much buildmagic to me. Maybe we can assume after checking in the xfce 4.16 everything is fine. Or we should better Buildrequire x11 >= 1.8.1 to be on the safe side?