@democrite,
Better yet. Qt devs tracked down and fixed an Accessibility bug and posted a patch online. I was able to rebuild Qt6.5.2 with their patch. To test it I fired up Rectangle.app and now no crashes inside non-native QFileDialogs on my arm64 machine.
I have posted a testbuild for Sigil with the Qt patches in place here:
https://github.com/kevinhendricks/Bu...OnMac/releases
Grab Sigil.app-testbuild-Mac-arm64.txz
Please give it a try and confirm if this fixes both the crash with Rectangle.app and with your Default Folder X app.
If so I will make this Qt6.5.2 bug patch part of the next official release.
Thank you for your bug report!