Qt屏蔽窗口关闭按钮

setWindowFlags(Qt::CustomizeWindowHint | 
               Qt::WindowMinimizeButtonHint | 
               Qt::WindowMaximizeButtonHint);

class Widget : public QWidget {
    Q_OBJECT
public:
    Widget() { }

    void closeEvent(QCloseEvent *event)
    {
     /* 忽略关闭事件 */
        event->ignore();
    }
};