Fix bug of window closing and reshowing

Sine Striker

2024-02-23 6c0043c1e3d97398828fbd56448f1cd8ee201e66

 examples/mainwindow/main.cpp

@@ -1,4 +1,5 @@
// Copyright (C) 2023-2024 Stdware Collections
// Copyright (C) 2023-2024 Stdware Collections (https://www.github.com/stdware)
// Copyright (C) 2021-2023 wangwenx190 (Yuhang Zhao)
// SPDX-License-Identifier: Apache-2.0

#include <QtWidgets/QApplication>
@@ -13,10 +14,11 @@
    qputenv("QSG_RHI_BACKEND", "d3d12");
    qputenv("QSG_RHI_HDR", "scrgb");
    qputenv("QT_QPA_DISABLE_REDIRECTION_SURFACE", "1");
#endif

    
    QGuiApplication::setHighDpiScaleFactorRoundingPolicy(
        Qt::HighDpiScaleFactorRoundingPolicy::PassThrough);
#endif

    QApplication a(argc, argv);

#if 0 && defined(Q_OS_WINDOWS) && QT_VERSION < QT_VERSION_CHECK(6, 0, 0)
@@ -30,5 +32,10 @@

    MainWindow w;
    w.show();

#if 0
    QMainWindow w2;
    w2.show();
#endif
    return a.exec();
}