fvwm seems to have problems keeping _NET_WORKAREA in sync with
the number of desktops. Instead of reading garbage, silently use
the full screen as workarea for desktops that are not covered
by the _NET_WORKAREA property.
https://bugzilla.gnome.org/show_bug.cgi?id=698248
goto out;
desktop = get_current_desktop (screen);
+ if (desktop + 1 > num / 4) /* fvwm gets this wrong */
+ goto out;
workareas = (long *) ret_workarea;
area->x = workareas[desktop * 4];