I have a user that has written replies in Flowdock that should be rethreaded to another chat. When I visit her computer I see she does NOT have the re-thread icon on her Chat message. What would prevent the icon from appearing? She also cannot drag and drop per the instruction.
In this case, you do not see a re-thread option on that particular message because you cannot rethread a starting message once it has been responded to. You can only rethread standalone messages before someone comments to it, or a non-first messages. For Ex:
Original message - can be rethreaded before it becomes a thread because someone commented
Original Message - cannot rethread once someone comments
Comment 1 - can be re-threaded
Comment 2 - can be re-threaded
Comment 3 - can be re-threaded
Hope that makes sense, let me know if you have more questions.
IMHO... enabling this capability is an important functionality that is missing -- accomplished at a minor effort