yes,there are entries as object_1,2 etc,all are for panel shortcuts and none was earlier there for GNOME Menu-bar.
But after i figured out the location of the icon and changed it to my icon,a new entry is there as:
object_7:containing all those what you explained :-|
earlier there was:
Now there is this entry automagically made:
see that earlier and now also no object_6 there.so may be this feature(icon editing) too is hidden in registry or "locked-down" may be.
As you are interested of this behaviour in GNOME,i have taken a screenshot of gconf-editor explaining things clearly.ya,i dint removed any entries,not yet fiddled on any entries