When a sandboxed (i.e. signed with entitlements) application is run on Mac OS X Lion calling the QFileDialog::getSaveFileName() method fails to show a save dialog and the system hangs. The application then no longer responds to any input.

If you run the Console app on Mac OS X there are also a number of related error messages and what looks to be a stack trace for the sandboxing system.

This has been reproduced by me and a few of my customers.

Running the same sandboxed app on OS X 10.8 (Mountain Lion) seems to work though. Also when running the same app outside of the sandbox the save dialog seems to work fine even on OS X Lion.