Software :: Pygtk - Updating Status Bar During Long Operation?

I'm trying to write a gui front-end for fsarchiver using pygtk. It mostly works, but I'd like to update the front-end's status bar while fsarchiver is running. I've placed the code for the actual call to fsarchiver in one thread, and the code to update the status bar in another thread as shown below. Messages from show_progress() get printed in the terminal window, as expected. I've tried adding

Code:
while gtk.events_pending():
gtk.main_iteration_do(False)

but obviously, I'm not doing it correctly because the status bar text does not update. Is what I'm trying to do possible, and, if so, how should it be coded?

Here's the code snippet from my calling routine:

Code:
self.activethreads=2
thread.start_new_thread(self.do_fsarchive, (my_cmd,))
print "start 2nd thread now
"
thread.start_new_thread(self.show_progress,(10,status_text))
And here are the two functions:
code....