Process pending Tk events from GObject main loop?

[Skip Montanaro]

I know I have things bassackwards, but trying to process Gtk events
from Tkinter's main loop using after() isn't working. (I suspect our
underlying C++ (ab)use of Gtk may require a Gtk main loop). I'd like
to process Tk events periodically from a GObject main loop. I know I
want to call gobject.idle_add(), but can't find Tkinter equivalent to
gobject.MainLoop().get_context().iteration(). That is, how do you
process a single event (or all pending events)? It looks like
_tkinter.dooneevent() might be the right call to process a single
event, but how do I tell no more events are pending?

Thx,

Skip