RWLock::WriterLock lock((*context)->get_rw_lock());
//synfig::info("%s: dirty_time=%f",(*context)->get_name().c_str(),(float)(*context)->dirty_time_);
RWLock::WriterLock lock((*context)->get_rw_lock());
//synfig::info("%s: dirty_time=%f",(*context)->get_name().c_str(),(float)(*context)->dirty_time_);