rem: rect.pos = sPtr->contentView->pos;
add: rect.pos.x = -sPtr->contentView->pos.x; rect.pos.y = -sPtr->contentView->pos.y;
context: WMGetScrollViewVisibleRect(WMScrollView *sPtr){    WMRect rect;        rect.pos = sPtr->contentView->pos;    rect.size = sPtr->viewport->size;        return rect;}