int backlogSize = model()->rowCount();
if(isSingleBufferScene() && backlogSize != 0 && _lastBacklogSize + REQUEST_COUNT <= backlogSize) {
QModelIndex msgIdx = model()->index(0, 0);
int backlogSize = model()->rowCount();
if(isSingleBufferScene() && backlogSize != 0 && _lastBacklogSize + REQUEST_COUNT <= backlogSize) {
QModelIndex msgIdx = model()->index(0, 0);