edit Gnome menu system-wide
 

How do i edit the gnome menu so that all users have the same menu?

in the home directory should be an invisible file called like .gnome-panel or something like that. it should have inside it the way your stuff is set up. so get it how you want, then cp -rf nameoffolder to /home/*/.gnome-panel. the * means every directory in the home folder gets the setting you have set for the gnome-panel. you know what i mean? let me know if not i have been drinking and stuff. if this makes any sense and you want more info let me know.

I have tried to find such a file but could not find it.

The files that were hidden and had something to do with gnome, only contained two -and some of them three- lines of which at least one contained a sentence stating that it should not be edited or that it is generated automatically and one with a reference to a file on another location.

The version of RH I use is 8.0

In Red Hat 9 I think what you're looking for is
.gnome2/panel2.d/default/launchers/