Stopwatch using PyGtk

stopwatch.py

import time
import gtk
import threading
import gobject 
gtk.gdk.threads_init()

class main():
    def __init__(self):       
        self.window = gtk.Window(gtk.WINDOW_TOPLEVEL)
        self.window.set_title('Stopwatch')
        self.window.set_size_request(200,200)
        self.table = gtk.Table(10,20,True)
        self.entry = gtk.Entry()
        self.entry.set_editable(False)
        self.table.attach(self.entry , 0 , 20 , 2 , 4)
        self.button = gtk.ToggleButton(label = 'Start')        
        self.button.connect('toggled' , self.count)
        self.table.attach(self.button , 6 , 14 ,  6 ,10)         
        self.image = gtk.Image()
        self.image.set_from_file('stop.jpg')
        self.table.attach(self.image , 0 ,20, 0 ,10)         
        self.window.add(self.table)        
        self.window.connect('delete-event' , gtk.main_quit) 
        self.window.show_all()

    def count(self,widget):        
        if widget.get_active():
            self.s = time.time()
            threading.Thread(target = self.ent_change).start()
            widget.set_label('Stop')
        else:                
            widget.set_label('Start')

    def ent_change(self):
        i = 0
        while 1:
            time.sleep(0.01)
            gobject.idle_add(self.change)
            i = i + 1
            if self.button.get_active() == 0:    
                break

    def change(self):
        show = time.time() - self.s        
        hour = show / 3600                
        minutes = (show % 3600) / 60
        seconds = show - (int(hour) * 3600) - (int(minutes) * 60)        
        string = ' %s : %s : %0.2f ' % (str(int(hour)),str(int(minutes)),seconds)
        self.entry.set_text(string)
          
     
if __name__ == '__main__':
    main()
    gtk.main()