{
  gboolean done_foo = FALSE, done_bar = FALSE;

  void
  foo_cb (yada)
  {
    done_foo = TRUE;
  }

  void
  bar_cb (yada)
  {
    done_bar = TRUE;
  }

  call_foo_async (yada, foo_cb);
  call_bar_async (yada, bar_cb);

  while (!done_foo || !done_bar)
    g_main_context_iterate ();

  ...continue...
}