Example of using Font Awesome in a PyGObject application.

app.py

# -*- coding: utf-8 -*-
#
# Copyright (C) 2014 Carlos Jenkins <carlos@jenkins.co.cr>
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
#   http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing,
# software distributed under the License is distributed on an
# "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
# KIND, either express or implied.  See the License for the
# specific language governing permissions and limitations
# under the License.

"""
Example of using Font Awesome in a PyGObject application.
"""

from gi.repository import Gtk


class MyApp(object):

    def __init__(self):
        """
        Build GUI
        """
        # States
        self.swap = False

        # Build GUI from Glade file
        self.builder = Gtk.Builder()
        self.builder.add_from_file('ui.glade')

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

        # 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
        """

        if self.swap:
            markup = (
                '<span font_desc="FontAwesome 30">&#xf113;</span>'
                '   '
                '<span font_desc="FontAwesome 30">&#xf0ac;</span>'
            )
        else:
            markup = (
                '<span fgcolor="#7c8dde" font_desc="FontAwesome 30">&#xf0e7;</span>'
                '   '
                '<span fgcolor="#26638c" font_desc="FontAwesome 30">&#xf182;</span>'
            )

        self.label.set_markup(markup)
        self.swap = not self.swap

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

ui.glade

<?xml version="1.0" encoding="UTF-8"?>
<!-- Generated with glade 3.16.1 -->
<interface>
  <requires lib="gtk+" version="3.10"/>
  <object class="GtkWindow" id="window">
    <property name="can_focus">False</property>
    <property name="window_position">center-always</property>
    <property name="default_width">300</property>
    <property name="default_height">300</property>
    <child>
      <object class="GtkBox" id="box">
        <property name="visible">True</property>
        <property name="can_focus">False</property>
        <property name="margin_left">5</property>
        <property name="margin_right">5</property>
        <property name="margin_top">5</property>
        <property name="margin_bottom">5</property>
        <property name="orientation">vertical</property>
        <child>
          <object class="GtkButton" id="button">
            <property name="visible">True</property>
            <property name="can_focus">True</property>
            <property name="receives_default">True</property>
            <signal name="clicked" handler="_btn_cb" swapped="no"/>
            <child>
              <object class="GtkLabel" id="button_label">
                <property name="visible">True</property>
                <property name="can_focus">False</property>
                <property name="label" translatable="yes">&lt;span font_desc="FontAwesome 30"&gt;&amp;#xf039;&lt;/span&gt;   &lt;span font_desc="FontAwesome 30"&gt;&amp;#xf17b;&lt;/span&gt;</property>
                <property name="use_markup">True</property>
              </object>
            </child>
          </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 font_desc="FontAwesome 30"&gt;&amp;#xf113;&lt;/span&gt;   &lt;span font_desc="FontAwesome 30"&gt;&amp;#xf0ac;&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>
      </object>
    </child>
  </object>
</interface>