Add menuitems runtime, strange warning

[Jesse van den Kieboom <troplosti@orcaweb.cjb.net>]

I'm using libglade to build my GUI from a glade xml file. It also
creates a menubar. After it is build I manually add some other
menuitems. This worked fine before, and adding the menuitems still works
okay. The items apear in the menu, but when I highlight a menuitem
(hovering the mouse pointer over the item) I get these warnings (only
with manually added items): 

(gnoemoe:3462): GLib-GObject-WARNING **: gsignal.c:2267: signal name
`selection_changed' is invalid for instance `0x811d0c0'

I guess this has something to do with glade now building the menu the
'gnome'-way. I'm using this to add menuitems:

gtk_menu_shell_append(GTK_MENU_SHELL(mnu), newItem);

(Also tried gtk_container_add, but it has the same effect). What am I
doing wrong here?

Jesse