Fix screen scaling factor calculation

For some users on Windows the physicalDotsPerInch() could return values
that are smaller than the normal 96 DPI which leads to big dialog sizes
taking the entire screen.
So we need to ensure it is at least 96 DPI.
Closes #11405, #11407.

src/gui/utils.cpp

@@ -68,7 +68,10 @@ qreal Utils::Gui::screenScalingFactor(const QWidget *widget)
 #ifdef Q_OS_WIN
     const int screenNumber = qApp->desktop()->screenNumber(widget);
     const QScreen *screen = QApplication::screens()[screenNumber];
-    return (screen->logicalDotsPerInch() / screen->physicalDotsPerInch());
+    // Workaround for QScreen::physicalDotsPerInch() that could return
+    // values that are smaller than the normal 96 DPI on Windows
+    const qreal physicalDPI = qMax<qreal>(screen->physicalDotsPerInch(), 96);
+    return (screen->logicalDotsPerInch() / physicalDPI);
 #elif defined(Q_OS_MACOS)
     return 1;
 #else