A simple skeleton Ubuntu indicator applet.

ubuntu-indicator.py

#!/usr/bin/env python
#
# Copyright 2013 Ramkumar Shankar
#
# Author: Ramkumar Shankar <ram.i.am@gmail.com>
#
# 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/>.

import sys
import os
import gtk
import appindicator
import pynotify

# Main class for the indicator
# Initialize and set up your methods here

class MyIndicator:
  
  def __init__(self):
    # initialization happens here
    self.init_notification()
    self.ind = appindicator.Indicator("my-indicator",
                                      self.set_idle_icon(),
                                      appindicator.CATEGORY_APPLICATION_STATUS)
    self.ind.set_attention_icon(self.set_attention_icon())
    self.ind.set_status(appindicator.STATUS_ACTIVE)
    self.menu_setup()
    self.ind.set_menu(self.menu)
    
  def set_idle_icon(self):
    ''' 
    The idle icon
    Keep the file in a folder named 'icons' where this python script resides
    and change the filename in the line below
    '''
    return os.path.dirname(os.path.realpath(__file__)) + os.path.sep + "icons" + os.path.sep + "idle_icon.png"
    
  def set_attention_icon(self):
    '''
    The attention icon
    Keep the file in a folder named 'icons' where this python script resides
    and change the filename in the line below
    '''
    return os.path.dirname(os.path.realpath(__file__)) + os.path.sep + "icons" + os.path.sep + "attention_icon.png"

  def init_notification(self):
    '''
    Create a notification to be displayed when menu items are clicked.
    This is just to initialize the object. We don't show anything yet.
    '''
    pynotify.init("my-indicator")
    self.myNotification = pynotify.Notification("something clicked",
                                           "responding to user input")

  def menu_setup(self):
    '''
    Indicator menu items are set up here. Change this as needed.
    We will set up a few different items for illustrative purposes
    '''
    self.menu = gtk.Menu()
    
    self.menu_item = gtk.MenuItem("Normal Item")
    self.check_item = gtk.CheckMenuItem("Set Attention")
    self.separator_item_1 = gtk.SeparatorMenuItem()
    self.radio_menu_group = gtk.RadioMenuItem()
    self.radio_item_1 = gtk.RadioMenuItem(self.radio_menu_group, "Radio Item 1")
    self.radio_item_2 = gtk.RadioMenuItem(self.radio_menu_group, "Radio Item 2")
    self.separator_item_2 = gtk.SeparatorMenuItem()
    self.quit_item = gtk.MenuItem("Quit")
    
    # make each item do something
    self.menu_item.connect("activate", self.click_menu_item)
    self.check_item.connect("toggled", self.toggle_check_item)
    self.radio_item_1.connect("activate", self.toggle_radio_item)
    self.radio_item_2.connect("activate", self.toggle_radio_item)
    self.quit_item.connect("activate", self.quit)
    
    # add each item to the menu
    self.menu.append(self.menu_item)
    self.menu.append(self.check_item)
    self.menu.append(self.separator_item_1)
    self.menu.append(self.radio_item_1)
    self.menu.append(self.radio_item_2)
    self.menu.append(self.separator_item_2)
    self.menu.append(self.quit_item)
    
    # show each item
    self.menu_item.show()
    self.check_item.show()
    self.separator_item_1.show()
    self.radio_item_1.show()
    self.radio_item_2.show()
    self.separator_item_2.show()
    self.quit_item.show()

  def main(self):
    # Main loop - starts the indicator
    gtk.main()
    
  def click_menu_item(self, widget):
    self.myNotification.update("menu item clicked",
                               "You could do something else here")
    self.myNotification.show()
    
  def toggle_check_item(self, widget):
    # when checked, toggle attention state too
    if widget.active:
      self.ind.set_status(appindicator.STATUS_ATTENTION)
      self.myNotification.update("check item activated",
                                 "my icon is now blue!")
      self.myNotification.show()
    else:
      self.ind.set_status(appindicator.STATUS_ACTIVE)
      self.myNotification.update("check item deactivated",
                                 "the icon is back to white now")
      self.myNotification.show()

  def toggle_radio_item(self, widget):
    self.myNotification.update(widget.get_label() + " selected")
    self.myNotification.show()
    
  def quit(self, widget):
    sys.exit(0)

if __name__ == "__main__":
  ind = MyIndicator()
  ind.main()