The user action time that will be passed to the channel dispatcher when requesting the channel.
This may be the time at which user action occurred, or one of the special values
USER_ACTION_TIME_NOT_USER_ACTION or
TP_USER_ACTION_TIME_CURRENT_TIME.
If USER_ACTION_TIME_NOT_USER_ACTION, the action doesn't involve any user action. Clients should avoid stealing focus when presenting the channel.
If TP_USER_ACTION_TIME_CURRENT_TIME, clients SHOULD behave as though the user action happened at the current time, e.g. a
client may request that its window gains focus.
On X11-based systems, GDK 2, GDK 3, Clutter 1.0 etc., user_action_time_from_x11 can be used to convert an X11 timestamp to a Telepathy user action time.
If the channel request succeeds, this user action time will be passed on to the channel's handler. If the handler is a GUI, it may use user_action_time_should_present to decide whether to bring its window to the foreground.