Размытый фон для QInputDialog

QInputDialog* win = new QInputDialog(this);          // создавать нужно именно так
win->setWindowFlags(Qt::FramelessWindowHint);
QGraphicsBlurEffect* effect = new QGraphicsBlurEffect;
win->setGraphicsEffect(effect);

#include <QApplication>
#include <QWidget>
#include <QGraphicsBlurEffect>
#include <QInputDialog>
#include <QLabel>
#include <QPushButton>
#include <QVBoxLayout>
 
class Window: public QWidget
{
  QInputDialog* win;
public:
  Window() : QWidget()
  {
    QLabel* label = new QLabel("label", this);
    QPushButton* button = new QPushButton("dialog", this);
    QVBoxLayout* layout = new QVBoxLayout();
    layout->addWidget(label);
    layout->addWidget(button);
    setLayout(layout);
    resize(500, 500);
    win = new QInputDialog(this, Qt::FramelessWindowHint);
    connect(button, &QPushButton::clicked, this, &Window::dialog);
  }
  void dialog()
  {
    QGraphicsBlurEffect* blur = new QGraphicsBlurEffect;
    setGraphicsEffect(blur);
    win->exec();
    setGraphicsEffect(nullptr);
  }
};
 
int main(int argc, char *argv[])
{
  QApplication app(argc, argv);
  Window window;
  window.show();
  return app.exec();
}