零碎代码段

//来源：Qt creator源码
class FilterWidget : public QWidget
{
public:
 //Qt::Popup 弹出窗口
 FilterWidget(QWidget *parent, QWidget *content) : QWidget(parent, Qt::Popup)
 {
     // 关闭即删除
     setAttribute(Qt::WA_DeleteOnClose);
     const auto layout = new QVBoxLayout(this);
     layout->setContentsMargins(2, 2, 2, 2);
     layout->setSpacing(2);
     layout->addWidget(content);
     setLayout(layout);
     move(parent->mapToGlobal(QPoint(0, -sizeHint().height())));
 }
};