> A proper solution IMO should somehow merge the selectors so that a
> single select() or whatever wakes up when either network I/O happens
> or a UI event comes in (which could be something that Tk transparently
> handles but it still needs to be given the chance, through
> root.update()).

I think we can do something similar to self-pipe trick: have a pipe
and a reader for it registered with 'loop.add_reader'. Whenever
a UI thread have an event to process, it should write a byte to the
pipe.

I'm not sure if there's a way to do that with Tk.