How to run PyOS_InputHook from python code (i.e. yield to event loops)

[Ville M. Vainio]

Background: PyOS_InputHook is something that gets run when python is
doing raw_input. TkInter and friends use it to run their event loops,
so that their events are handled while python is doing raw_input.

What I'd like to do is run the same function without having to do
raw_input. I.e. I'd like to run whatever event loop is available,
without incorporating any gui-specific code (PyOS_InputHook seems like
a nifty way to accomplish this).

My actual use case is to keep a tkinter application responsive while
launching a background process (and waiting for it to complete!).

My eventual code would be something like:

launch_process_in_thread('bzr pull')

while not is_done:
  pyos_inputhook()
  time.sleep(0.1)

print "Done!"