If a property has a reload function, but the standard property-fetching
mechanism isn't used (hooks->type == META_PROP_VALUE_INVALID), then the
a logic error (introduced in January) caused the hook to never be run.
This meant that changes to struts and icons weren't noticed.
Same as: http://bugzilla.gnome.org/show_bug.cgi?id=572573
The fix here is different in detail from that applied to Metacity, but
similar in spirit.
http://bugzilla.gnome.org/show_bug.cgi?id=585980