def register_global_command(self, command, title=None, group=None):
        '''
        .. versionadded:: 0.13


        Register global command (i.e., not specific to electrode or route).

        Add global command to context menu.
        '''
        commands = self.global_commands.setdefault(group, OrderedDict())
        if title is None:
            title = (command[:1].upper() + command[1:]).replace('_', ' ')
        commands[command] = title