Glade files mark properties for translation with the translatable property of the <property> element:

<widget class="GtkLabel" id="label1">
  <property name="label" translatable="yes">Foo</property>
  ...
</widget>

Libglade will translate marked properties using the translation domain specified in the glade_xml_new() (or the default domain if NULL).

Libglade also supports disambiguating properties by prefixing them with a |-separated context string, e.g. "Menu/Printer|Open" vs. "Menu/File|Open". You must tell Libglade that the property has a prefix by setting the context attribute of the <property> element to "yes". To learn more about this technique, read the chapter "How to use gettext in GUI programs" in the gettext manual, and see the GLib API documentation for g_strip_context().

To add the strings found in a glade file to your translation catalog template through the use of intltool. (XXXX - does this actually work yet?).