void MainWindow::contextMenuEvent(QContextMenuEvent* event)
{
QMenu menu;
// 关键的两行代码
menu.setWindowFlags(Qt::FramelessWindowHint);
menu.setAttribute(Qt::WA_TranslucentBackground);
menu.setStyleSheet("QMenu{ "
"background-color: rgb(255, 255, 255);"
"border-radius: 20px; "
"}"
"QMenu::item { background-color: transparent;"
"padding:3px 20px;"
"margin:5px 10px;"
"}"
"QMenu::item:selected { background-color: gray; }"
);
menu.addAction("打开",this,SLOT(open()));
menu.addSeparator();
menu.addAction("关闭",this,SLOT(close()));
menu.exec(QCursor::pos());
}