docs: def _get_selected_library_state(self):
          """Returns the LibraryState which was selected in the LibraryTree
  
          :return: selected state in TreeView
          :rtype: LibraryState
          """
          library_os_path, library_path, library_name, item_key = self.extract_library_properties_from_selected_row()
          if library_path is None:
              return None
  
          logger.debug("Link library state '{0}' (with library tree path: {2} and file system path: {1}) into state "
                       "machine.".format(str(item_key), library_os_path,
                                         self.convert_if_human_readable(str(library_path)) + "/" + str(item_key)))
          library_name = library_os_path.split(os.path.sep)[-1]
          return LibraryState(library_path, library_name, "0.1", format_folder_name_human_readable(library_name))