/* 0: check status, 1: don't, -1: disallow change silently */
FOREACH_RESULT(I_OnLocalTopicChange,OnLocalTopicChange(u,this,ntopic));
/* 0: check status, 1: don't, -1: disallow change silently */
FOREACH_RESULT(I_OnLocalTopicChange,OnLocalTopicChange(u,this,ntopic));