ChatStateFilter requires an empty body
From: Rob Napier <rnapier@xxxxxxxxx>
Date: Fri, 11 Dec 2009 01:54:48 +0100 (CET)
ChatStateFilter only calls handleChatState() if msg.body().empty():

      if( m_enableChatStates && msg.body().empty() )
        m_chatStateHandler->handleChatState( msg.from(), state->state() );

While I can just set chat state back to Active any time a non-empty message 
comes in, this seems an unnecessary special case in the code. Why the 
msg.body().empty() test? Can this be removed?

-Rob