Qt Cocoa Applications won't quit correctly on Log Out or Shutdown

Start for example the Browser.app Demo compiled with Qt/Cocoa.
Select Apple Menu/Log out or Apple Menu/Shutdown

This will give you a messagebox saying "The application XYZ canceled logout".

This does not happen with Qt/Carbon.

I suspect that

• (NSApplicationTerminateReply)applicationShouldTerminate:(NSApplication *)sender
  {
  /* ... */
  return NSTerminateCancel;
  }

has something to do with this?