title: button Stop/Cancel progressBar from subprocess PYGTK
body: <p>I have been trying to add a cancel button to a progressbar en pygtk but now way to get the funcion. What its does that function is execute and script and every line in the output count it and is added to the progressBar. My problem is how to cancel that subprocess, is there a way? </p>
  
  <pre><code>def stop(self, widget):
      print "cancelar"
      os.killpg(self.p.pid, signal.SIGTERM) #=&gt; not working
      self.p.kill() #=&gt; not working
  
  
  count = 0
  command = "script.sh"
  self.p = subprocess.Popen(command, shell=True, bufsize=0, stdout=subprocess.PIPE, universal_newlines=True)
  
  
  for line in iter(self.p.stdout.readline, ""):
      count = count + 1
  
      while gtk.events_pending():
          gtk.mainiteration()
          gobject.timeout_add(1000, self.update)
          porcentaje = float(count) / float(1400)
          print porcentaje
          self.progress.set_text(str(int(porcentaje * 100)) + "%")
          self.progress.set_fraction(porcentaje)
  </code></pre>