PageItem::startRender should probably return the number of tiles and hence render tasks it has requested to start rendering so that DocumentView::on_prefetch_timeout can accomodate for this being larger than one in its prefetching budget.
PageItem: :startRender should probably return the number of tiles and hence render tasks it has requested to start rendering so that DocumentView: :on_prefetch_ timeout can accomodate for this being larger than one in its prefetching budget.