Sends a getMdxSessionStatus to get the screenId and waits for response.
        This function is blocking
        If connected we should always get a response
        (send message will launch app if it is not running).

def update_screen_id(self):
        """
        Sends a getMdxSessionStatus to get the screenId and waits for response.
        This function is blocking
        If connected we should always get a response
        (send message will launch app if it is not running).
        """
        self.status_update_event.clear()
        # This gets the screenId but always throws. Couldn't find a better way.
        try:
            self.send_message({MESSAGE_TYPE: TYPE_GET_SCREEN_ID})
        except UnsupportedNamespace:
            pass
        self.status_update_event.wait()
        self.status_update_event.clear()