If "show text near icons" is selected in the gnome global toolbar preferences, the "use global gnome config" option for the toolbar of gthumb (in the properties window of gthumb) makes only some names to appear with the icons in the toolbar, as expected, but they appear under the icons, not at the side. Only selecting "text near icons" makes them appear that way. That "use gnome global configuration" option should have the same result without having to explicitly selecting it.
reproducable. should push upstream
http://bugzilla.gnome.org/show_bug.cgi?id=160003