Finally, I understand why, at some point, all the app-defaults disappeared. I had to fix them manually, now I know the cause.
Graham Bloice wrote:
Installing LessTif-0.93.18-3 creates a directory in /usr/X11R6/lib/X11 named app-defaults. This overrides the symbolic link placed there by XFree86-lib post install pointing to /etc/X11. Amongst other things this breaks XCalc. Regards, Graham Bloice
