If your actions are small enough, you could try to do the trick I used in a simpleminded modular synthesizer: replace your MainLoop with something like:

  while (1) {
    DoOneEvent(DONT_WAIT);
    # do your own (short) action
    select undef,undef,undef,0.0001;
  }
[download]

It's not perfect, but if your code can be broken up like this, it's pretty easy to implement.