Qt6 port:

* Constructor of QFontDatabase is deprecated, use static functions instead
* Fix QuantitySpinBox::selectNumber()
* Fix InputField::selectNumber()
* Make InputField::fixup() compatible with Qt6
* QFont::setWeight requires an enum now
* QInputEvent reuires a pointing device now
* QAbstractItemView::viewOptions() has been renamed to QAbstractItemView::initViewItemOption()

src/Gui/Tree.cpp

@@ -4776,7 +4776,13 @@ void DocumentObjectItem::testStatus(bool resetStatus, QIcon& icon1, QIcon& icon2
         // get the original icon set
         QIcon icon_org = object()->getIcon();
 
+#if QT_VERSION < QT_VERSION_CHECK(6,0,0)
         int w = getTree()->viewOptions().decorationSize.width();
+#else
+        QStyleOptionViewItem opt;
+        getTree()->initViewItemOption(&opt);
+        int w = opt.decorationSize.width();
+#endif
 
         QPixmap pxOn, pxOff;