GtkToolButton with image file

[Henry Feng <xhfeng westlakemicrosystems com>]

I have the following xml toolbutton description generated from 
glade-3.4.3(converted by gtk-builder-convert, GTK 2.16.0), the image 
shows up ok with glade, but the gtk application could not display the 
image on the button and got run time warning "Gtk-WARNING **: Unknown 
property: GtkToolButton.icon"

Looked into the gtktoolbutton.c, it supports only icon-widget and 
icon-name property, what can I do to load the image to the button?

           <child>
             <object class="GtkToolButton" id="toolbutton_trigger">
               <property name="visible">True</property>
               <property name="label" translatable="yes">Trigger</property>
               <property name="icon">trigger.png</property>
               <signal handler="on_toolbutton_trigger_clicked" 
name="clicked"/>
             </object>
             <packing>
               <property name="homogeneous">True</property>
             </packing>
           </child>

--
Thanks,

HFeng