простейший пример.
import appuifw as aw
import e32
lock = e32.Ao_lock()
def select1():
func2()
def func1():
aw.app.body = lb1
aw.app.exit_key_handler = lock.signal
def func2():
aw.app.body = lb2
aw.app.exit_key_handler = func1
lb1 = aw.Listbox([u'item_lb1_1', u'item_lb1_2'], select1)
lb2 = aw.Listbox([u'item_lb2_1', u'item_lb2_2'])
func1()
lock.wait()
txtfield - модуль от watt