取消选中QGraphicsItem后的虚线框

重写paint函数

void ShapeLine::paint(QPainter *painter, const QStyleOptionGraphicsItem *option, QWidget *widget)
{
    QStyleOptionGraphicsItem op;
    op.initFrom(widget);
    op.state = QStyle::State_None;

    return QGraphicsLineItem::paint(painter, &op, widget);
}