My PyGObject template files for simple applications.

gui.glade

<?xml version="1.0" encoding="UTF-8"?>
<interface>
  <!-- interface-requires gtk+ 3.0 -->
  <object class="GtkWindow" id="window">
    <property name="can_focus">False</property>
    <property name="border_width">10</property>
    <property name="title" translatable="yes">Ejemplo PyGtk</property>
    <property name="window_position">center-always</property>
    <property name="default_width">400</property>
    <property name="default_height">300</property>
    <child>
      <object class="GtkVBox" id="body">
        <property name="visible">True</property>
        <property name="can_focus">False</property>
        <property name="spacing">5</property>
        <child>
          <object class="GtkImage" id="image">
            <property name="visible">True</property>
            <property name="can_focus">False</property>
            <property name="pixbuf">logo.png</property>
          </object>
          <packing>
            <property name="expand">True</property>
            <property name="fill">True</property>
            <property name="position">0</property>
          </packing>
        </child>
        <child>
          <object class="GtkLabel" id="label">
            <property name="visible">True</property>
            <property name="can_focus">False</property>
            <property name="label" translatable="yes">&lt;span foreground="#2075AD" size="xx-large" weight="bold"&gt;This is a label&lt;/span&gt;</property>
            <property name="use_markup">True</property>
          </object>
          <packing>
            <property name="expand">True</property>
            <property name="fill">True</property>
            <property name="position">1</property>
          </packing>
        </child>
        <child>
          <object class="GtkHButtonBox" id="footer">
            <property name="visible">True</property>
            <property name="can_focus">False</property>
            <child>
              <object class="GtkButton" id="button">
                <property name="label" translatable="yes">Please do click</property>
                <property name="use_action_appearance">False</property>
                <property name="visible">True</property>
                <property name="can_focus">True</property>
                <property name="receives_default">True</property>
                <property name="use_action_appearance">False</property>
                <signal name="clicked" handler="_btn_cb" swapped="no"/>
              </object>
              <packing>
                <property name="expand">False</property>
                <property name="fill">False</property>
                <property name="position">0</property>
              </packing>
            </child>
          </object>
          <packing>
            <property name="expand">True</property>
            <property name="fill">True</property>
            <property name="position">2</property>
          </packing>
        </child>
      </object>
    </child>
  </object>
</interface>

logo.png

main.py

# -*- coding:utf-8 -*-
#
# Copyright (C) 2013 Carlos Jenkins <carlos@jenkins.co.cr>
#
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program.  If not, see <http://www.gnu.org/licenses/>.

"""
PyGObject example with Glade and GtkBuilder.

Check dependencies are installed:

    sudo apt-get install python2.7 python-gi gir1.2-gtk-3.0

To execute:

    python main.py

Python reference still unavailable, nevertheless C reference documentation is
available at:

    https://developer.gnome.org/gtk3/

And a good tutorial at:

    https://python-gtk-3-tutorial.readthedocs.org/en/latest/index.html

"""

from gi.repository import Gtk
from os.path import abspath, dirname, join

WHERE_AM_I = abspath(dirname(__file__))

class MyApp(object):

    def __init__(self):
        """
        Build GUI
        """

        # Declare states / variables
        self.counter = 0

        # Build GUI from Glade file
        self.builder = Gtk.Builder()
        self.glade_file = join(WHERE_AM_I, 'gui.glade')
        self.builder.add_from_file(self.glade_file)

        # Get objects
        go = self.builder.get_object
        self.window = go('window')
        self.button = go('button')

        # Connect signals
        self.builder.connect_signals(self)

        # Configure interface
        self.window.connect('delete-event', lambda x,y: Gtk.main_quit())

        # Everything is ready
        self.window.show()

    def _btn_cb(self, widget, data=None):
        """
        Button callback
        """
        self.counter += 1
        print('Button pressed {} times.'.format(self.counter))


if __name__ == '__main__':
    gui = MyApp()
    Gtk.main()