glade make me a .glade files like this
<?xml version="1.0" encoding="UTF-8" standalone="no"?>
<!DOCTYPE glade-interface SYSTEM "glade-2.0.dtd">
<!--Generated with glade3 3.4.5 on Sun Jul 27 19:42:14 2008 -->
<glade-interface>
<widget class="GtkWindow" id="prova!">
<child>
<widget class="GtkFixed" id="fixed1">
<property name="visible">True</property>
<child>
<widget class="GtkButton" id="button1">
<property name="width_request">100</property>
<property name="height_request">80</property>
<property name="visible">True</property>
<property name="can_focus">True</property>
<property name="receives_default">True</property>
<property name="label" translatable="yes">OK</property>
<property name="response_id">0</property>
</widget>
<packing>
<property name="x">188</property>
<property name="y">93</property>
</packing>
</child>
</widget>
</child>
</widget>
</glade-interface>
and i haven't found an Export option... :( i don't know how to do :(
in worst case i use the wx... maybe in a next version are expected an gtk gui designer?