While learning more about how to implement services with QtDBus, I noticed that TpQt4 doesn't call setDelayedReply(true) on the DBusMessage; from my reading of the documentation, this means that ObserveChannels() is returning immediately, rather than waiting for the library user's implementation to signal that it's ready to return from ObserveChannels(). We should check if this actually works.

(Thiago Macieira informs us that having a DBusMessage argument in the adaptor's method implementation is deprecated—in some nebulous fashion which does not involve marking it as such in the documentation :-)—in favour of the exported object (not adaptor) deriving from DBusContext and calling magic methods to get the current connection and message, etc. But possibly switching to that is orthogonal to checking this potential bug out.)