The --gui option does not seem to work consistently across ipython versions. I understand why you might not want to use --pylab because of namespace pollution, but at least check whether your app works with it. You could also try the %gui magic instead of --gui.
BTW, for you and all list subscribers -- the list was stuck again for the past few weeks, so old messages are only appearing now. Apologies -- the list manager is past due to be migrated to a more robust server.