Питон во вложении, а в гладе добавить это.
<child>
<object class="IconFileSelection" id="iconview1">
<property name="icon_size">32</property>
<property name="start_dir">/home/cnc/linuxcnc/nc_files/</property>
<property name="filetypes">ngc</property>
<signal name="selected" handler="on_selected" swapped="no"/>
</object>
<placeholder/>
</child>