#include <QApplication>
#include "mainwindow.h"

int main(int argc, char *argv[])
{
    QApplication app(argc, argv);

    // Retina display support for Mac OS, iOS and X11:
    // http://blog.qt.digia.com/blog/2013/04/25/retina-display-support-for-mac-os-ios-and-x11/
    //
    // AA_UseHighDpiPixmaps attribute is off by default in Qt 5.1 but will most
    // likely be on by default in a future release of Qt.
    app.setAttribute(Qt::AA_UseHighDpiPixmaps);

    QIcon appIcon;
    appIcon.addFile(":/Icons/AppIcon32");
    appIcon.addFile(":/Icons/AppIcon128");
    app.setWindowIcon(appIcon);

    MainWindow mainWindow;
    mainWindow.show();
    return app.exec();
}

#include <QApplication>
#include "mainwindow.h"

int main(int argc, char *argv[])
{
    QApplication app(argc, argv);

    app.setAttribute(Qt::AA_UseHighDpiPixmaps);

    QIcon appIcon;
    appIcon.addFile(":/Icons/AppIcon32");
    appIcon.addFile(":/Icons/AppIcon128");
    app.setWindowIcon(appIcon);

    MainWindow mainWindow;
    mainWindow.show();
    return app.exec();
}

--- 
+++ 
@@ -5,6 +5,11 @@
 {
     QApplication app(argc, argv);
 
+    // Retina display support for Mac OS, iOS and X11:
+    // http://blog.qt.digia.com/blog/2013/04/25/retina-display-support-for-mac-os-ios-and-x11/
+    //
+    // AA_UseHighDpiPixmaps attribute is off by default in Qt 5.1 but will most
+    // likely be on by default in a future release of Qt.
     app.setAttribute(Qt::AA_UseHighDpiPixmaps);
 
     QIcon appIcon;
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