GTK+ dialogs crash on Wayland

When running a gnome/wayland session, trying to open a file dialog results in a crash. Affected applications include Qt Creator, Calibre, and basically any other application using native file, color or font dialogs. Easy to reproduce with qtbase/tests/manual/dialogs.

traceback:

#0 0x000055731d033d30 in ?? ()
#1 0x00007ff949f873a6 in XChangeProperty (dpy=0x55731d0328a0, w=0, property=property@entry=68, type=type@entry=33,
format=format@entry=32, mode=mode@entry=0, data=0x7fff46edcb68 "\025", nelements=1) at ChProp.c:92
#2 0x00007ff949fa5509 in XSetTransientForHint (dpy=<optimized out>, w=<optimized out>, propWindow=<optimized out>)
at SetHints.c:286
#3 0x00007ff932284d3e in QGtk3Dialog::show(QFlags<Qt::WindowType>, Qt::WindowModality, QWindow*) ()
from /usr/lib64/qt5/plugins/platformthemes/libqgtk3.so
#4 0x00007ff9322879d1 in QGtk3FileDialogHelper::show(QFlags<Qt::WindowType>, Qt::WindowModality, QWindow*) ()
from /usr/lib64/qt5/plugins/platformthemes/libqgtk3.so
#5 0x00007ff94cd10e60 in QDialogPrivate::setNativeDialogVisible(bool) () from /lib64/libQt5Widgets.so.5
#6 0x00007ff94cd23552 in QFileDialog::setVisible(bool) () from /lib64/libQt5Widgets.so.5
#7 0x00007ff94cd11d0a in QDialog::exec() () from /lib64/libQt5Widgets.so.5
#8 0x00007ff94cd2405a in QFileDialog::getOpenFileUrls(QWidget*, QString const&, QUrl const&, QString const&, QString*, QFlags<QFileDialog::Option>, QStringList const&) () from /lib64/libQt5Widgets.so.5
#9 0x00007ff94cd242bf in QFileDialog::getOpenFileNames(QWidget*, QString const&, QString const&, QString const&, QString*, QFlags<QFileDialog::Option>) () from /lib64/libQt5Widgets.so.5
#10 0x00007ff94d2bfbe1 in meth_QFileDialog_getOpenFileNames ()
from /usr/lib64/python2.7/site-packages/PyQt5/QtWidgets.so
#11 0x00007ff958bf739f in PyEval_EvalFrameEx () from /lib64/libpython2.7.so.1.0
#12 0x00007ff958bfa07c in PyEval_EvalCodeEx () from /lib64/libpython2.7.so.1.0
#13 0x00007ff958b82e3d in function_call () from /lib64/libpython2.7.so.1.0
#14 0x00007ff958b5dff3 in PyObject_Call () from /lib64/libpython2.7.so.1.0
#15 0x00007ff958b6ce4c in instancemethod_call () from /lib64/libpython2.7.so.1.0
#16 0x00007ff958b5dff3 in PyObject_Call () from /lib64/libpython2.7.so.1.0
#17 0x00007ff958bb5117 in slot_tp_init () from /lib64/libpython2.7.so.1.0
#18 0x00007ff958bb3dde in type_call () from /lib64/libpython2.7.so.1.0
#19 0x00007ff958b5dff3 in PyObject_Call () from /lib64/libpython2.7.so.1.0
#20 0x00007ff958bf5e96 in PyEval_EvalFrameEx () from /lib64/libpython2.7.so.1.0
#21 0x00007ff958bfa07c in PyEval_EvalCodeEx () from /lib64/libpython2.7.so.1.0
#22 0x00007ff958bf6fb1 in PyEval_EvalFrameEx () from /lib64/libpython2.7.so.1.0
#23 0x00007ff958bfa07c in PyEval_EvalCodeEx () from /lib64/libpython2.7.so.1.0
#24 0x00007ff958b82d5c in function_call () from /lib64/libpython2.7.so.1.0
#25 0x00007ff958b5dff3 in PyObject_Call () from /lib64/libpython2.7.so.1.0
#26 0x00007ff958b6ce4c in instancemethod_call () from /lib64/libpython2.7.so.1.0
#27 0x00007ff958b5dff3 in PyObject_Call () from /lib64/libpython2.7.so.1.0
#28 0x00007ff958bf0127 in PyEval_CallObjectWithKeywords () from /lib64/libpython2.7.so.1.0
#29 0x00007ff94870a1e8 in PyQtSlot::call(_object*, _object*) const ()
from /usr/lib64/python2.7/site-packages/PyQt5/QtCore.so
#30 0x00007ff94870a630 in PyQtSlot::invoke(void*, _object, void*, bool) const ()
from /usr/lib64/python2.7/site-packages/PyQt5/QtCore.so
#31 0x00007ff94870b1d0 in PyQtSlotProxy::unislot(void**) () from /usr/lib64/python2.7/site-packages/PyQt5/QtCore.so
#32 0x00007ff94870bc47 in PyQtSlotProxy::qt_metacall(QMetaObject::Call, int, void**) ()
from /usr/lib64/python2.7/site-packages/PyQt5/QtCore.so
#33 0x00007ff94c30316b in QMetaObject::activate(QObject*, int, int, void**) () from /lib64/libQt5Core.so.5
#34 0x00007ff94cb1df52 in QAction::triggered(bool) () from /lib64/libQt5Widgets.so.5
#35 0x00007ff94cb20982 in QAction::activate(QAction::ActionEvent) () from /lib64/libQt5Widgets.so.5
#36 0x00007ff94cc0d5bd in QAbstractButtonPrivate::click() () from /lib64/libQt5Widgets.so.5
#37 0x00007ff94cc0d804 in QAbstractButton::mouseReleaseEvent(QMouseEvent*) () from /lib64/libQt5Widgets.so.5
#38 0x00007ff94ccd981a in QToolButton::mouseReleaseEvent(QMouseEvent*) () from /lib64/libQt5Widgets.so.5
--Type <return> to continue, or q <return> to quit--
#39 0x00007ff94cb6bc30 in QWidget::event(QEvent*) () from /lib64/libQt5Widgets.so.5
#40 0x00007ff94ccd9902 in QToolButton::event(QEvent*) () from /lib64/libQt5Widgets.so.5
#41 0x00007ff94cb2496c in QApplicationPrivate::notify_helper(QObject*, QEvent*) () from /lib64/libQt5Widgets.so.5
#42 0x00007ff94cb2cfcd in QApplication::notify(QObject*, QEvent*) () from /lib64/libQt5Widgets.so.5
#43 0x00007ff94d31f26e in sipQApplication::notify(QObject*, QEvent*) ()
from /usr/lib64/python2.7/site-packages/PyQt5/QtWidgets.so
#44 0x00007ff94c2dc12a in QCoreApplication::notifyInternal2(QObject*, QEvent*) () from /lib64/libQt5Core.so.5
#45 0x00007ff94cb2b65d in QApplicationPrivate::sendMouseEvent(QWidget*, QMouseEvent*, QWidget*, QWidget*, QWidget**, QPointer<QWidget>&, bool) () from /lib64/libQt5Widgets.so.5
#46 0x00007ff94cb85dd0 in QWidgetWindow::handleMouseEvent(QMouseEvent*) () from /lib64/libQt5Widgets.so.5
#47 0x00007ff94cb88603 in QWidgetWindow::event(QEvent*) () from /lib64/libQt5Widgets.so.5
#48 0x00007ff94cb2496c in QApplicationPrivate::notify_helper(QObject*, QEvent*) () from /lib64/libQt5Widgets.so.5
#49 0x00007ff94cb2c111 in QApplication::notify(QObject*, QEvent*) () from /lib64/libQt5Widgets.so.5
#50 0x00007ff94d31f26e in sipQApplication::notify(QObject*, QEvent*) ()
from /usr/lib64/python2.7/site-packages/PyQt5/QtWidgets.so
#51 0x00007ff94c2dc12a in QCoreApplication::notifyInternal2(QObject*, QEvent*) () from /lib64/libQt5Core.so.5
#52 0x00007ff94c61ae73 in QGuiApplicationPrivate::processMouseEvent(QWindowSystemInterfacePrivate::MouseEvent*) ()
from /lib64/libQt5Gui.so.5
#53 0x00007ff94c61c925 in QGuiApplicationPrivate::processWindowSystemEvent(QWindowSystemInterfacePrivate::WindowSystemEvent*) () from /lib64/libQt5Gui.so.5
#54 0x00007ff94c5fd7cb in QWindowSystemInterface::sendWindowSystemEvents(QFlags<QEventLoop::ProcessEventsFlag>) ()
from /lib64/libQt5Gui.so.5
#55 0x00007ff932336c60 in userEventSourceDispatch(_GSource*, int (void*), void*) () from /lib64/libQt5XcbQpa.so.5
#56 0x00007ff94e276f02 in g_main_context_dispatch () from /lib64/libglib-2.0.so.0
#57 0x00007ff94e277280 in g_main_context_iterate.isra () from /lib64/libglib-2.0.so.0
#58 0x00007ff94e27732c in g_main_context_iteration () from /lib64/libglib-2.0.so.0
#59 0x00007ff94c329d6f in QEventDispatcherGlib::processEvents(QFlags<QEventLoop::ProcessEventsFlag>) ()
from /lib64/libQt5Core.so.5
#60 0x00007ff94c2db0ba in QEventLoop::exec(QFlags<QEventLoop::ProcessEventsFlag>) () from /lib64/libQt5Core.so.5
#61 0x00007ff94c2e2bac in QCoreApplication::exec() () from /lib64/libQt5Core.so.5
#62 0x00007ff94d31da6b in meth_QApplication_exec_ () from /usr/lib64/python2.7/site-packages/PyQt5/QtWidgets.so
#63 0x00007ff958bf739f in PyEval_EvalFrameEx () from /lib64/libpython2.7.so.1.0
#64 0x00007ff958bfa07c in PyEval_EvalCodeEx () from /lib64/libpython2.7.so.1.0
#65 0x00007ff958bf6fb1 in PyEval_EvalFrameEx () from /lib64/libpython2.7.so.1.0
#66 0x00007ff958bfa07c in PyEval_EvalCodeEx () from /lib64/libpython2.7.so.1.0
#67 0x00007ff958bf6fb1 in PyEval_EvalFrameEx () from /lib64/libpython2.7.so.1.0
#68 0x00007ff958bfa07c in PyEval_EvalCodeEx () from /lib64/libpython2.7.so.1.0
#69 0x00007ff958bf6fb1 in PyEval_EvalFrameEx () from /lib64/libpython2.7.so.1.0
#70 0x00007ff958bfa07c in PyEval_EvalCodeEx () from /lib64/libpython2.7.so.1.0
#71 0x00007ff958bfa169 in PyEval_EvalCode () from /lib64/libpython2.7.so.1.0
#72 0x00007ff958c1354f in run_mod () from /lib64/libpython2.7.so.1.0
#73 0x00007ff958c14782 in PyRun_FileExFlags () from /lib64/libpython2.7.so.1.0
#74 0x00007ff958c15995 in PyRun_SimpleFileExFlags () from /lib64/libpython2.7.so.1.0
#75 0x00007ff958c27920 in Py_Main () from /lib64/libpython2.7.so.1.0
#76 0x00007ff957e41421 in __libc_start_main () from /lib64/libc.so.6
#77 0x000055731b5a97ba in _start ()

There's also a message before the crash:

(python2:10369): GLib-GObject-WARNING **: invalid cast from 'GdkWaylandDisplay' to 'GdkX11Display'