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/SoTextLabel.cpp

@@ -407,7 +407,7 @@ void SoFrameLabel::drawImage()
         return;
     }
 
-    QFont font(QString::fromLatin1(name.getValue()), size.getValue());
+    QFont font(QString::fromLatin1(QByteArray(name.getValue())), size.getValue());
     QFontMetrics fm(font);
     int w = 0;
     int h = fm.height() * num;