Check if a user is typing using App Engine XMPP

The XMPP service in GAE is great and all, but I'm really interested in when a user opens up a window to send a message, or when he/s开发者_运维问答he starts typing. I think XMPP supports this, because Pidgin does this, as does Google Talk, so why not the XMPP/GAE service?

Unfortunately App Engine doesn't pass in Chat State notifications to the application, so you won't be able to receive notifications of a user typing a message ("composing") until they actually send it.