Problem when handling form submission with WebKitGTK+ 2.14

webkitgtk_form.py

# To run: install (Ubuntu package names)
# ``python3-gi``, ``gir1.2-gtk-3.0``, ``gir1.2-webkit2-4.0``,
# then do ``python3 webkitgtk_form.py``

import ctypes

import gi
gi.require_version('Gtk', '3.0')
gi.require_version('WebKit2', '4.0')
from gi.repository import Gtk, WebKit2


def main():
    window = Gtk.Window()
    window.connect('delete-event', lambda *_: Gtk.main_quit())
    view = WebKit2.WebView()
    window.add(view)
    view.connect('submit-form', on_submit_form, [])
    view.load_html('<form> <input name=foo> <input type=submit> </form>')
    window.show_all()
    Gtk.main()


def on_submit_form(view, request, refs):
    # Handle the form submission (= do something with the submitted data).
    for k, v in request.get_text_fields().items():
        # Note how I have to do the extra `ctypes.string_at` step,
        # because `k` and `v` are pointers (Python integers, not bytestrings).
        # I think this may be a bug, but it's unrelated to my problem.
        print(ctypes.string_at(k) + b'=' + ctypes.string_at(v))

    # After handling the form, we want to prevent its further submission.
    # This works with WebKitGTK+ 2.12, but under 2.14 the WebView just "hangs".
    refs.append(request)


if __name__ == '__main__':
    main()