Qt6 port:

* Explicitly include some missing headers
* Use 'static const char*' for XPM icon
* Skip template parameters for qMakePair
* Constructor of QFileInfo is marked as 'explicit' now
* QString::fromLatin1() also accepts a QByteArray
* QDateTime::fromTime_t() is deprecated in Qt5 and has been removed in Qt6. Use QDateTime::fromSecsSinceEpoch()
* QDateTime::toTime_t() is deprecated in Qt5 and has been removed in Qt6. Use QDateTime::toSecsSinceEpoch()
* QApplication::globalStrut() is deprecated. Don't use it any more.
* QWidget::isTopLevel() is deprecated, use QWidget::isWindow()

src/Gui/GuiApplication.cpp

@@ -60,8 +60,8 @@ using namespace Gui;
 GUIApplication::GUIApplication(int & argc, char ** argv)
     : GUIApplicationNativeEventAware(argc, argv)
 {
-    connect(this, SIGNAL(commitDataRequest(QSessionManager &)),
-            SLOT(commitData(QSessionManager &)), Qt::DirectConnection);
+    connect(this, SIGNAL(commitDataRequest(QSessionManager&)),
+            SLOT(commitData(QSessionManager&)), Qt::DirectConnection);
 #if QT_VERSION < QT_VERSION_CHECK(6,0,0)
     setFallbackSessionManagementEnabled(false);
 #endif