lablgtk-2.4.0 has a conditional DEPEND on libgnomecanvas, gnome-panel and libgnomui. However, it does not pass these optional dependencies as options to configure. Thus, I got lablgtk linked against the gnome libraries that I have installed temporarily (USE=-gnome, gnome libs installed). I found bug #87426, which I thought is a dup of this, but even though closely related, I don't think it is. So, please add the appropriate ... whatever $(use_with gnome panel) $(use_with gnome gnomeui) $(use_with gnome gnomecanvas) as these are listed as conditional dependencies, and I don't want my library to break if I decide to remove the gnome libs.
I added use_with calls for gnome, svg, glade & opengl, thanks for reminding me of the other bug and giving me the code needed ;)