Open Radar

 
Summary: 
NSOpenPanel hangs when the application is sandboxed, canChooseDirectories is set to YES, and the delegate is using -panel:shouldEnableURL:

Steps to Reproduce: 
1. Create a new project in Xcode
2. Sandbox the application with user selected file read/write access
3. Set the AppDelegate to conform to the NSOpenSavePanelDelegate
4. Open the MainMenu.xib and add a button linked to the action chooseFolder: as follows:
- (IBAction)chooseFolder:(id)sender {
   NSOpenPanel *openPanel = [NSOpenPanel openPanel];

   [openPanel setCanChooseDirectories:YES];
   [openPanel setDelegate:self];

    [openPanel beginSheetModalForWindow:self.window completionHandler:^(NSInteger result) {
       NSLog(@"Finished");
    }];
}
5. Add the -panel:shouldEnableURL: delegate method as follows:
-(BOOL)panel:(id)sender shouldEnableURL:(NSURL *)url{
   return YES;
}
6. Run the application and click the button to open the panel.

Expected Results:  The panel to open and allow me to select a directory

Actual Results: The application will hang.

Regression:

Notes: -panel:shouldEnableURL: is never called when the application hangs, the CPU doesn't appear to spike.