Is there any special reason for this ?
>From GTk Docs
(http://library.gnome.org/devel/gtk/unstable/GtkSettings.html#GtkSettings
--gtk-button-images):
The "gtk-button-images" property
Whether images should be shown on buttons.
Default value: TRUE
So this is not documented and it's not behaving a
Public bug reported:
>From gtk documentation
(http://library.gnome.org/devel/gtk/unstable/GtkButton.html#gtk-button-
set-image):
gtk_button_set_image ()
Set the image of button to the given widget. Note that it depends on the
"gtk-button-images" setting whether the image will be displayed or not