Loop stops after dialog goes away

Please disregard if I’m doing something bone-headed. It may be due to my lack, of either asyncio or Qt knowledge.

I’m trying to show two dialogs, one after the other. In this small example I use QWizard’s After the first one goes away either by pressing cancel or finish, I get the error shown below. However, if I have a button sitting there in the background it behaves just fine. If instead of running run_until_complete(amain()) I run asyncio.ensure_future(amain()) followed by loop.run_forever() then I don’t get any errors but the 2nd wizard never shows up. It just exists as soon as there is nothing left to display on the screen.

#!/usr/bin/env python3
import asyncio
import sys

from PyQt5.QtWidgets import QApplication, QWizard, QWizardPage, QDialog, QPushButton
from quamash import QEventLoop


def async_dialog_exec(dlg: QDialog):
    fut = asyncio.Future()
    dlg.finished.connect(lambda result: fut.set_result(result))
    dlg.open()
    return fut

async def amain():
    # if these two lines are uncommented you'll be able to see both wizards
    # b = QPushButton('hi')
    # b.show()
    wiz1 = QWizard()
    wiz1.addPage(QWizardPage())
    wiz1.setWindowTitle("First Wizard")
    result = await async_dialog_exec(wiz1)
    if result != QDialog.Accepted:
        return

    wiz2 = QWizard()
    wiz2.addPage(QWizardPage())
    wiz2.setWindowTitle("Second Wizard")
    result = await async_dialog_exec(wiz2)
    if result != QDialog.Accepted:
        return

app = QApplication(sys.argv)
loop = QEventLoop(app)
asyncio.set_event_loop(loop)
with loop:
    loop.run_until_complete(amain())

Traceback (most recent call last):
  File "/home/vagrant/PycharmProjects/test/dlg_example.py", line 37, in <module>
    loop.run_until_complete(amain())
  File "/opt/Python-3/lib/python3.5/site-packages/quamash/__init__.py", line 270, in run_until_complete
    raise RuntimeError('Event loop stopped before Future completed.')
RuntimeError: Event loop stopped before Future completed.

[harvimt]

adding app.setQuitOnLastWindowClosed(False) makes everything work correctly.

[harvimt]

replicated on windows. In all cases the problem is that the loop exits when all windows are closed, so a dummy window that keeps the app open and the

do to the magic of duck typing, this will work:

app = QApplication(sys.argv)
wiz1 = QWizard()
wiz1.addPage(QWizardPage(wiz1))
wiz1.setWindowTitle("First Wizard")
loop = QEventLoop(wiz1)
asyncio.set_event_loop(loop)
with loop:
    loop.run_forever()

wiz2 = QWizard()
wiz2.addPage(QWizardPage(wiz2))
wiz2.setWindowTitle("Second Wizard")
loop = QEventLoop(wiz2)
asyncio.set_event_loop(loop)
with loop:
    loop.run_forever()