The signals for the action group were being disconnected when the action
group was explicitly removed from the GActionMuxer but the same was not
being done when it was finalized.
This means that a change in the state of an action group that used to be
associated with a finalized GActionMuxer would result in a crash. This
would happen for stateful application actions after closing a window.
https://bugzilla.gnome.org/show_bug.cgi?id=681399
We now have GRemoteActionGroup interface with the needed API,
implemented by GDBusActionGroup.
With the new API we could theoretically turn GActionMuxer itself into a
GRemoteActionGroup and expose the _full API to the shell so that the
timestamps could be passed from there.
Pass the current timestamp as platform data when activating
an action. This is implemented slightly hacky, since we use
clutter_get_current_event_time() to get at the timestamp, but
the alternative is to expose g_action_muxer_activate_action_full
to js, which would be quite a bit more involved.
GDBusActionGroup api has changed again, adapt to that.
Also, use a GActionMuxer to add the 'app.' prefix to actions,
instead of manually stripping it out of the action names.
In the future, the muxer will also contain per-window actions
with a 'win.' prefix.
