Apologies if you frequent Stack Overflow and have seen me ask this same question there, but it's getting precious little attention over there.

I'm programming a simple pyS60 app, not really done anything with python or using multiple threads before so this is all a bit new to me. In order to keep the app open, I set an e32.Ao_lock to wait() after the body of the application is initialised, and then signal the lock on the exit_key_handler.

One of the tasks the program may do is open a third party app, UpCode. This scans a barcode and copies the barcode string to the clipboard. When I close UpCode, my application should resume and paste the input from the clipboard. I know this can be accomplished using Ao.lock, but I've already called an instance of this. Ideally my application would regain focus after noticing something had been pasted to the clipboard. Can I accomplish what I need with one of the sleep or timer functions?

You can find the full script here, and I've abbreviated it to the necessary parts below:
Code:
lock=e32.Ao_lock()

# Quit the script
def quit():
    lock.signal()

# Callback function will be called when the requested service is complete. 
def launch_app_callback(trans_id, event_id, input_params):
    if trans_id != appmanager_id and event_id != scriptext.EventCompleted:
        print "Error in servicing the request"
        print "Error code is: " + str(input_params["ReturnValue"]["ErrorCode"])
        if "ErrorMessage" in input_params["ReturnValue"]:
            print "Error message is: " + input_params["ReturnValue"]["ErrorMessage"]
    else:
        print "\nWaiting for UpCode to close"
    #lock.signal()

# launch UpCode to scan barcode and get barcode from clipboard
def scan_barcode():
    msg('Launching UpCode to scan barcode.\nPlease exit UpCode after the barcode has been copied to the clipboard')
    # Load appmanage service
    appmanager_handle = scriptext.load('Service.AppManager', 'IAppManager')
    # Make a request to query the required information in asynchronous mode
    appmanager_id = appmanager_handle.call('LaunchApp', {'ApplicationID': u's60uid://0x2000c83e'}, callback=launch_app_callback)
    #lock.wait()
    #print "Request complete!"
    barcode = clipboard.Get()
    return barcode

# handle the selection made from the main body listbox
def handle_selection():
    if (lb.current() == 0):
        barcode = scan_barcode()
    elif (lb.current() ==1):
        barcode = clipboard.Get()
    elif (lb.current() ==2):
        barcode = input_barcode()

    found = False
    if is_barcode(barcode):
        found, mbid, album, artist = identify_release(barcode)
    else:
        msg('Valid barcode not found. Please try again/ another method/ another CD')
        return

    if found:
        go = appuifw.query(unicode('Found: ' + artist + ' - ' + album + '\nScrobble it?'), 'query')
        if (go == 1):
            now = datetime.datetime.utcnow()
            scrobble_tracks(mbid, album, artist, now)
        else:
            appuifw.note(u'Scrobbling cancelled', 'info')
    else:
        appuifw.note(u'No match found for this barcode.', 'info')

# Set the application body up
appuifw.app.exit_key_handler = quit
appuifw.app.title = u"ScanScrobbler"
entries = [(u"Scan a barcode", u"Opens UpCode for scanning"),
           (u"Submit barcode from clipboard", u"If you've already copied a barcode there"),
           (u"Enter barcode by hand", u"Using numeric keypad")
          ]

lb = appuifw.Listbox(entries, handle_selection)
appuifw.app.body = lb

lock.wait()
Any and all help appreciated.