fActiveSourceWorker
if (window->fActiveSourceWorker == find_thread(NULL)) {
if (fActiveSourceWorker < 0) {
fActiveSourceWorker = spawn_thread(&_RetrieveMatchingSourceWorker,
if (fActiveSourceWorker > 0)
resume_thread(fActiveSourceWorker);
if (fActiveSourceWorker > 0)
wait_for_thread(fActiveSourceWorker, NULL);
fActiveSourceWorker = -1;
thread_id fActiveSourceWorker;