[REG 6.8.2 -> 6.8.3] QFileDialog::getOpenFilename() and friends fail under sway

In Qt 6.8.3 QFileDialog::getOpenFileName() with am application event loop fails, showing no dialog and returning. If run without an application event loop it works. This is a regression from 6.8.2 where it worked in both cases. Note this seems to be sway specific, it works on KDE, GNOME and Hyprland compositors. Trivial reproducer using pySide:

from PySide6.QtWidgets import QApplication, QFileDialog
from PySide6.QtCore import QTimer
def get():
    print('calling getOpenFileName()')
    print('returned:', QFileDialog.getOpenFileName(None))app = QApplication([])if if False:
    get()
else:
    QTimer.singleShot(100, get)
    app.exec() 

Run the above under sway as

XDG_CURRENT_DESKTOP=sway python test.py  

and observer failure, no file dialog is shown. Now change If False to if True and see that the file dialog is shown, as expected. Also fails with XDG_CURRENT_DESKTOP=sway:kde