Steps to reproduce:
1. Create a New Project in Glade 3.x
2. Drop the default GtkMenuBar into a GtkWindow.
3. Run through gtk-builder-convert


Stack trace:
The default GtkImageMenuItem's in glade are "stock" menus which output a "use_stock" property such as following:


  <widget class="GtkImageMenuItem" id="new_menu_item">
    <property name="visible">True</property>
    <property name="events">GDK_POINTER_MOTION_MASK | GDK_POINTER_MOTION_HINT_MASK | GDK_BUTTON_PRESS_MASK | GDK_BUTTON_RELEASE_MASK</property>
    <property name="label" translatable="yes">_New</property>
    <property name="use_underline">True</property>
    <property name="use_stock">True</property>
    <signal name="activate" handler="on_new_menu_item_activate"/>
  </widget>


When you try to run this through gtk-builder-convert you get the following error:


Traceback (most recent call last):

+ Trace 197957

This can be worked around by changing all default GtkImageMenuItem's in glade to "Stock" = 'None' and instead set the "Label" manually and apply a stock image under 'Internal Image Properties'. That results in the following:

  <widget class="GtkImageMenuItem" id="new_menu_item">
    <property name="visible">True</property>
    <property name="events">GDK_POINTER_MOTION_MASK | GDK_POINTER_MOTION_HINT_MASK | GDK_BUTTON_PRESS_MASK | GDK_BUTTON_RELEASE_MASK</property>
    <property name="label" translatable="yes">_New</property>
    <property name="use_underline">True</property>
    <signal name="activate" handler="on_new_menu_item_activate"/>
    <child internal-child="image">
      <widget class="GtkImage" id="menu-item-image1">
        <property name="stock">gtk-new</property>
      </widget>
    </child>
  </widget>


Other information:
Confirmed on Ubuntu "Gutsy" and "Hardy", GTK+ 2.12.9, Glade 3.x