void documentController_DocumentHandlerAdded(DocumentController docCtrlr)
        {
            List <String> readableDocuments = new List <string>(documentGrid
                                                                .itemsInGroup(DocumentController.UnknownDocumentGroup)
                                                                .Select(i => i.UserObject as String)
                                                                .Where(i => docCtrlr.canReadFile(i)));

            foreach (String doc in readableDocuments)
            {
                removeDocument(doc);
                addDocument(doc);
            }
        }