[glade--] Gtk::Button with image only

What's the easiest way to get a plain button with an image and no label? 
  I'm still using Gtkmm 2.4 and I noticed there are a couple new methods 
in Gtk::Button in 2.6 for images.

I'm designing this through Glade ver 2.6.8.  When I try and add a 
Gtk::Image to a Gtk::Button in my code, it complains at runtime that the 
button already has a Gtk::Label in it.  Is there a way to delete that 
Gtk::Label in Glade or am I stuck having to generate the button in my code.