formatting and now subclassing is tested by Open a document

Tests/Manual/CPDocumentControllerTest/withNib/DocumentController.j

@@ -12,4 +12,12 @@
     return [CPDocumentController sharedDocumentController];
 }
 
+/* Instead of throwing error in browser environment, show an alert
+ */
+- (void)openDocument:(id)aSender
+{
+    var anAlert = [CPAlert alertWithError:@"Opening a document is not available!"];
+    [anAlert beginSheetModalForWindow:[[CPApplication sharedApplication] mainWindow]];
+}
+
 @end