Currently, if a contact is invisible, we don't have any capabilities for them. Because we only send chat state notifications to contacts who advertise support for it, we don't send chat state notifications to invisible contacts. XEP-0085 defines a method to implicitly request and discover support for chat state notifications, even if you don't know that the other contact supports that capability. If we supported it, then we'd be able to send typing notifications to offline contacts, and then I wouldn't get told off for not using the Google Talk client. http://xmpp.org/extensions/xep-0085.html#bizrules
Was bored, and implemented this in my 'chat-states' branch.
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Merged to master; will be released in 0.9.3.
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