Remove the -I part of show-messages which isn't really that useful; the

server start time can now be accessed with a new start_time format (use:
tmux display -p '#{t:start_time}')

format.c

@@ -488,6 +488,8 @@ format_create_flags(int flags)
 	format_add_cb(ft, "host", format_cb_host);
 	format_add_cb(ft, "host_short", format_cb_host_short);
 	format_add_cb(ft, "pid", format_cb_pid);
+	format_add(ft, "socket_path", "%s", socket_path);
+	format_add_tv(ft, "start_time", &start_time);
 
 	return (ft);
 }