diff --git a/src/blackgui/blackgui.pro b/src/blackgui/blackgui.pro
index 43ee47b90..9b454e1ea 100644
--- a/src/blackgui/blackgui.pro
+++ b/src/blackgui/blackgui.pro
@@ -25,6 +25,9 @@ else {
     QMAKE_CXXFLAGS += -idirafter $$EXTERNALSROOT/common/include/qwt
 }
 
+# needed for "ShellScalingApi.h" only
+# win32 { LIBS *= -lSHCore }
+
 DEPENDPATH += . ..
 
 PRECOMPILED_HEADER = pch/pch.h
diff --git a/src/blackgui/guiapplication.cpp b/src/blackgui/guiapplication.cpp
index 16460e005..dae3b97f8 100644
--- a/src/blackgui/guiapplication.cpp
+++ b/src/blackgui/guiapplication.cpp
@@ -66,6 +66,7 @@
 #include <QMessageBox>
 #include <QtGlobal>
 #include <QWhatsThis>
+#include <Qt>
 
 using namespace BlackConfig;
 using namespace BlackMisc;
@@ -351,21 +352,27 @@ namespace BlackGui
         CApplication::exit(retcode);
     }
 
-    void CGuiApplication::highDpiScreenSupport(double scaleFactor)
+    void CGuiApplication::highDpiScreenSupport(const QString &scaleFactor)
     {
         // https://lists.qt-project.org/pipermail/development/2019-September/037434.html
-        if (scaleFactor < 0)
+        // QSize s = CGuiUtility::physicalScreenSizeOs();
+        QString sf = scaleFactor.trimmed().isEmpty() ? defaultScaleFactorString() : scaleFactor;
+        if (sf.contains('/'))
         {
-            // qputenv("QT_AUTO_SCREEN_SCALE_FACTOR", "1"); // until 5.14
-            qputenv("QT_ENABLE_HIGHDPI_SCALING", "1");
-        }
-        else
-        {
-            QApplication::setAttribute(Qt::AA_EnableHighDpiScaling); // DPI support
-            QCoreApplication::setAttribute(Qt::AA_UseHighDpiPixmaps); // HiDPI pixmaps
-            const QString sf = QString::number(scaleFactor, 'f', 2);
-            qputenv("QT_SCALE_FACTOR", sf.toLatin1());
+            const double sfd = parseFraction(scaleFactor, -1);
+            sf = sfd < 0 ? "1.0" : QString::number(sfd, 'f', 8);
         }
+
+        sf = cleanNumber(sf);
+
+        QApplication::setAttribute(Qt::AA_EnableHighDpiScaling);  // DPI support
+        QCoreApplication::setAttribute(Qt::AA_UseHighDpiPixmaps); // HiDPI pixmaps
+
+        // qputenv("QT_ENABLE_HIGHDPI_SCALING", "1");
+        QGuiApplication::setHighDpiScaleFactorRoundingPolicy(Qt::HighDpiScaleFactorRoundingPolicy::Floor);
+
+        const QByteArray sfa = sf.toLatin1();
+        qputenv("QT_SCALE_FACTOR", sfa);
     }
 
     bool CGuiApplication::isUsingHighDpiScreenSupport()
@@ -375,7 +382,7 @@ namespace BlackGui
 
     QScreen *CGuiApplication::currentScreen()
     {
-        QWidget *w = CGuiApplication::mainApplicationWidget();
+        const QWidget *w = CGuiApplication::mainApplicationWidget();
         const int s = QApplication::desktop()->screenNumber(w);
         if (s < QGuiApplication::screens().size()) { return QGuiApplication::screens()[s]; }
         return QGuiApplication::primaryScreen();
@@ -552,6 +559,37 @@ namespace BlackGui
         return -1.0;
     }
 
+    QString CGuiApplication::scaleFactor(int argc, char *argv[])
+    {
+        for (int i = 1; i < argc; ++i)
+        {
+            if (qstrcmp(argv[i], "--scale") == 0 || qstrcmp(argv[i], "-scale") == 0)
+            {
+                if (i + 1 >= argc) { return QString(); } // no value
+                const QString factor(argv[i + 1]);
+                return factor.trimmed();
+            }
+        }
+        return QString();
+    }
+
+    QString CGuiApplication::defaultScaleFactorString()
+    {
+        if (!CBuildConfig::isRunningOnWindowsNtPlatform()) { return "1.0"; }
+
+        // On windows
+        // Qt 5.14.1 default is device ratio 3
+        // Qt 5.14.0 default device ratio was 2
+
+        // 2/3 (0.66667) => device ratio 3
+        // 0.75 => device ratio 2.25
+        // 0.8  => device ratio 2.4
+        // 1.00 => device ratio 3
+
+        // currently NOT used
+        return "1.0";
+    }
+
     bool CGuiApplication::cmdLineErrorMessage(const QString &errorMessage, bool retry) const
     {
         const QString helpText(beautifyHelpMessage(m_parser.helpText()));
diff --git a/src/blackgui/guiapplication.h b/src/blackgui/guiapplication.h
index d47f80adc..c6caa9f4d 100644
--- a/src/blackgui/guiapplication.h
+++ b/src/blackgui/guiapplication.h
@@ -284,7 +284,7 @@ namespace BlackGui
 
         //! Support for high DPI screens
         //! \note Needs to be at the beginning of main
-        static void highDpiScreenSupport(double scaleFactor = -1);
+        static void highDpiScreenSupport(const QString &scaleFactor = {});
 
         //! Uses the high DPI support?
         static bool isUsingHighDpiScreenSupport();
@@ -300,8 +300,15 @@ namespace BlackGui
         static void modalWindowToFront();
 
         //! Parse scale factor if any
+        //! \deprecated using scaleFactor now
         static double parseScaleFactor(int argc, char *argv[]);
 
+        //! Get the scale factor
+        static QString scaleFactor(int argc, char *argv[]);
+
+        //! Get a default scale factor
+        static QString defaultScaleFactorString();
+
     signals:
         //! Style sheet changed
         void styleSheetsChanged();
diff --git a/src/blackgui/guiutility.cpp b/src/blackgui/guiutility.cpp
index b82fce791..7615f52a8 100644
--- a/src/blackgui/guiutility.cpp
+++ b/src/blackgui/guiutility.cpp
@@ -43,6 +43,14 @@
 #include <QPropertyAnimation>
 #include <QDesktopWidget>
 
+// for the screen size
+
+#ifdef Q_OS_WINDOWS
+#include "wtypes.h"
+#include "ShellScalingApi.h"
+#include <iostream>
+#endif
+
 using namespace BlackMisc;
 
 namespace BlackGui
@@ -114,6 +122,79 @@ namespace BlackGui
         return QApplication::desktop()->screenGeometry(QApplication::desktop()).size();
     }
 
+    QSizeF CGuiUtility::physicalScreenSize(QWidget *currentWidget)
+    {
+        QScreen *s = QGuiApplication::screens().front();
+        if (currentWidget)
+        {
+            const int sn = QApplication::desktop()->screenNumber(currentWidget);
+            s = QGuiApplication::screens().at(sn);
+        }
+
+        if (!s) { return QSizeF(); }
+        const QSizeF ps1 = s->physicalSize();
+        return ps1;
+    }
+
+    namespace Private
+    {
+#ifdef Q_OS_WINDOWS
+        QSize windowsGetDesktopResolution()
+        {
+            /**
+            // https://stackoverflow.com/questions/8690619/how-to-get-screen-resolution-in-c
+            RECT desktop;
+            // Get a handle to the desktop window
+            const HWND hDesktop = GetDesktopWindow();
+            // Get the size of screen to the variable desktop
+            GetWindowRect(hDesktop, &desktop);
+            // The top left corner will have coordinates (0,0)
+            // and the bottom right corner will have coordinates
+            // (horizontal, vertical)
+            const int horizontal = desktop.right;
+            const int vertical   = desktop.bottom;
+            return QSize(vertical, horizontal);
+            **/
+
+            // https://stackoverflow.com/questions/2156212/how-to-get-the-monitor-screen-resolution-from-a-hwnd
+            const HWND hDesktop = GetDesktopWindow();
+            HMONITOR monitor = MonitorFromWindow(hDesktop, MONITOR_DEFAULTTONEAREST);
+            MONITORINFO info;
+            info.cbSize = sizeof(MONITORINFO);
+            GetMonitorInfo(monitor, &info);
+
+            /**
+            DEVICE_SCALE_FACTOR pScale;
+            GetScaleFactorForMonitor(monitor, &pScale);
+            **/
+
+            const int monitor_width  = info.rcMonitor.right  - info.rcMonitor.left;
+            const int monitor_height = info.rcMonitor.bottom - info.rcMonitor.top;
+            return QSize(monitor_height, monitor_width);
+
+            /**
+            // https://stackoverflow.com/a/50205813/356726
+            const int width  = static_cast<int>(GetSystemMetrics(SM_CXSCREEN));
+            const int height = static_cast<int>(GetSystemMetrics(SM_CYSCREEN));
+            return QSize(width, height);
+            **/
+        }
+#endif
+    } // namespace Private
+
+    QSize CGuiUtility::physicalScreenSizeOs()
+    {
+#ifdef Q_OS_WINDOWS
+        return Private::windowsGetDesktopResolution();
+#elif defined(Q_OS_MAC)
+        return QSize();
+#elif defined(Q_OS_LINUX)
+        return QSize();
+#else
+        return QSize();
+#endif
+    }
+
     bool CGuiUtility::isMainWindowFrameless()
     {
         const CEnableForFramelessWindow *mw = CGuiUtility::mainFramelessEnabledWindow();
@@ -122,8 +203,15 @@ namespace BlackGui
 
     QString CGuiUtility::screenInformation(const QString &separator)
     {
+        const QSize ps = physicalScreenSizeOs();
         QString i = u"Number of screens: " % QString::number(QGuiApplication::screens().size()) % separator %
-                    u"Primary screen: " % QGuiApplication::primaryScreen()->name();
+                    u"Primary screen: " % QGuiApplication::primaryScreen()->name() % separator %
+                    u"QT_AUTO_SCREEN_SCALE_FACTOR: " % qgetenv("QT_AUTO_SCREEN_SCALE_FACTOR") % separator %
+                    u"QT_SCALE_FACTOR: " % qgetenv("QT_SCALE_FACTOR") % separator %
+                    u"QT_ENABLE_HIGHDPI_SCALING: " % qgetenv("QT_ENABLE_HIGHDPI_SCALING") % separator %
+                    u"QT_SCALE_FACTOR_ROUNDING_POLICY: " % qgetenv("QT_SCALE_FACTOR_ROUNDING_POLICY") % separator %
+                    u"QT_SCREEN_SCALE_FACTORS: " % qgetenv("QT_SCREEN_SCALE_FACTORS") % separator %
+                    u"OS screen res." % QString::number(ps.width()) % u"/" % QString::number(ps.height()) % separator;
 
         for (const QScreen *screen : QGuiApplication::screens())
         {
@@ -509,7 +597,7 @@ namespace BlackGui
         else
         {
             flags &= ~Qt::WindowStaysOnBottomHint;
-            flags |= Qt::WindowStaysOnTopHint;
+            flags |=  Qt::WindowStaysOnTopHint;
         }
         widget->setWindowFlags(flags);
         widget->show(); // without that the window sometimes just disappears
@@ -523,7 +611,7 @@ namespace BlackGui
         if (onTop)
         {
             flags &= ~Qt::WindowStaysOnBottomHint;
-            flags |= Qt::WindowStaysOnTopHint;
+            flags |=  Qt::WindowStaysOnTopHint;
         }
         else
         {
diff --git a/src/blackgui/guiutility.h b/src/blackgui/guiutility.h
index be1dd2227..41a7cdb2b 100644
--- a/src/blackgui/guiutility.h
+++ b/src/blackgui/guiutility.h
@@ -66,6 +66,14 @@ namespace BlackGui
         //! \remark might be scaled depending on CGuiUtility::mainApplicationWidgetPixelRatio
         static QSize desktopSize();
 
+        //! Pysical screen resolution
+        //! \remark unscaled
+        static QSizeF physicalScreenSize(QWidget *currentWidget = nullptr);
+
+        //! Qt independent implementation
+        //! \remark allows to return values before QGuiApplication is initialized
+        static QSize physicalScreenSizeOs();
+
         //! Is main window frameless?
         static bool isMainWindowFrameless();
 
diff --git a/src/blackmisc/stringutils.cpp b/src/blackmisc/stringutils.cpp
index 33a490231..3c7496023 100644
--- a/src/blackmisc/stringutils.cpp
+++ b/src/blackmisc/stringutils.cpp
@@ -491,6 +491,64 @@ namespace BlackMisc
         return (c % 2) == 0;
     }
 
+    double parseFraction(const QString &fraction, double failDefault)
+    {
+        if (fraction.isEmpty()) { return failDefault; }
+        bool ok;
+
+        double r = failDefault;
+        if (fraction.contains('/'))
+        {
+            const QStringList parts = fraction.split('/');
+            if (parts.size() != 2) { return failDefault; }
+            const double c = parts.front().trimmed().toDouble(&ok);
+            if (!ok) { return failDefault; }
+
+            const double d = parts.last().trimmed().toDouble(&ok);
+            if (!ok) { return failDefault; }
+            if (qFuzzyCompare(0.0, d)) { return failDefault; }
+            r = c / d;
+        }
+        else
+        {
+            r = fraction.trimmed().toDouble(&ok);
+            if (!ok) { return failDefault; }
+        }
+        return r;
+    }
+
+    QString cleanNumber(const QString &number)
+    {
+        QString n = number.trimmed();
+        if (n.isEmpty()) { return QString(); }
+
+        int dp = n.indexOf('.');
+        if (dp < 0) { dp = n.indexOf(','); }
+
+        // clean all trailing stuff
+        while (dp >= 0 && !n.isEmpty())
+        {
+            const QChar l = n.at(n.size() - 1);
+            if (l == '0')
+            {
+                n.chop(1);
+                continue;
+            }
+            else if (l == '.' || l == ',')
+            {
+                n.chop(1);
+            }
+            break;
+        }
+
+        while (n.startsWith("00"))
+        {
+            n.remove(0, 1);
+        }
+
+        return n;
+    }
+
 } // ns
 
 //! \endcond
diff --git a/src/blackmisc/stringutils.h b/src/blackmisc/stringutils.h
index a5e44e419..c47dd0b0d 100644
--- a/src/blackmisc/stringutils.h
+++ b/src/blackmisc/stringutils.h
@@ -308,6 +308,12 @@ namespace BlackMisc
     //! Contains any string of the list?
     BLACKMISC_EXPORT bool containsAny(const QString &testString, const QStringList &any, Qt::CaseSensitivity cs);
 
+    //! Parse a fraction like 2/3
+    BLACKMISC_EXPORT double parseFraction(const QString &fraction, double failDefault = std::numeric_limits<double>::quiet_NaN());
+
+    //! Remove leading 0, trailing 0, " ", and "." from a number
+    BLACKMISC_EXPORT QString cleanNumber(const QString &number);
+
     namespace Mixin
     {
         /*!
diff --git a/src/swiftcore/main.cpp b/src/swiftcore/main.cpp
index f66caa69c..44bda373d 100644
--- a/src/swiftcore/main.cpp
+++ b/src/swiftcore/main.cpp
@@ -27,7 +27,7 @@ using namespace BlackGui;
 int main(int argc, char *argv[])
 {
     //! [SwiftApplicationDemo]
-    CGuiApplication::highDpiScreenSupport(CGuiApplication::parseScaleFactor(argc, argv));
+    CGuiApplication::highDpiScreenSupport(CGuiApplication::scaleFactor(argc, argv));
     QApplication qa(argc, argv);
     Q_UNUSED(qa) // init of qa is required, but qa not used
 
diff --git a/src/swiftdata/main.cpp b/src/swiftdata/main.cpp
index 9174d80eb..9d1471286 100644
--- a/src/swiftdata/main.cpp
+++ b/src/swiftdata/main.cpp
@@ -25,9 +25,9 @@ using namespace BlackGui;
 
 int main(int argc, char *argv[])
 {
-    CGuiApplication::highDpiScreenSupport(CGuiApplication::parseScaleFactor(argc, argv));
+    CGuiApplication::highDpiScreenSupport(CGuiApplication::scaleFactor(argc, argv));
     QApplication qa(argc, argv);
-    Q_UNUSED(qa);
+    Q_UNUSED(qa)
 
     CCrashHandler::instance()->init();
     CGuiApplication a(CApplicationInfo::swiftMappingTool(), CApplicationInfo::MappingTool, CIcons::swiftDatabase48());
diff --git a/src/swiftguistandard/main.cpp b/src/swiftguistandard/main.cpp
index 8bcf6d39c..6533bd548 100644
--- a/src/swiftguistandard/main.cpp
+++ b/src/swiftguistandard/main.cpp
@@ -24,7 +24,7 @@ using namespace BlackCore;
 int main(int argc, char *argv[])
 {
     //! [SwiftApplicationDemo]
-    CGuiApplication::highDpiScreenSupport(CGuiApplication::parseScaleFactor(argc, argv));
+    CGuiApplication::highDpiScreenSupport(CGuiApplication::scaleFactor(argc, argv));
     QApplication qa(argc, argv);
     Q_UNUSED(qa) // application init needed
 
diff --git a/src/swiftguistandard/swiftguistdinit.cpp b/src/swiftguistandard/swiftguistdinit.cpp
index 5d69695f5..ed61fec99 100644
--- a/src/swiftguistandard/swiftguistdinit.cpp
+++ b/src/swiftguistandard/swiftguistdinit.cpp
@@ -76,7 +76,8 @@ void SwiftGuiStd::init()
     sGui->initMainApplicationWidget(this);
 
     // experimental: avoid mic flickering
-    if (CBuildConfig::isLocalDeveloperDebugBuild()) { BlackSound::occupyAudioInputDevice(); }
+    // disabled for 5.14.1
+    // if (CBuildConfig::isLocalDeveloperDebugBuild()) { BlackSound::occupyAudioInputDevice(); }
 
     // log messages
     m_logSubscriber.changeSubscription(CLogPattern().withSeverityAtOrAbove(CStatusMessage::SeverityInfo));
diff --git a/src/swiftlauncher/main.cpp b/src/swiftlauncher/main.cpp
index c0e1a7b04..cef5fa0cc 100644
--- a/src/swiftlauncher/main.cpp
+++ b/src/swiftlauncher/main.cpp
@@ -29,7 +29,7 @@ using namespace BlackCore::Db;
 int main(int argc, char *argv[])
 {
     //! [SwiftApplicationDemo]
-    CGuiApplication::highDpiScreenSupport(CGuiApplication::parseScaleFactor(argc, argv));
+    CGuiApplication::highDpiScreenSupport(CGuiApplication::scaleFactor(argc, argv));
     QApplication qa(argc, argv); // needed
     Q_UNUSED(qa)
     CGuiApplication a(CApplicationInfo::swiftLauncher(), CApplicationInfo::Laucher, CIcons::swiftLauncher1024());
diff --git a/src/swiftlauncher/swiftlauncher.cpp b/src/swiftlauncher/swiftlauncher.cpp
index 1e0daba8b..627131b77 100644
--- a/src/swiftlauncher/swiftlauncher.cpp
+++ b/src/swiftlauncher/swiftlauncher.cpp
@@ -483,7 +483,7 @@ void CSwiftLauncher::startButtonPressed()
 {
     const QObject *sender = QObject::sender();
     const qreal scaleFactor = ui->comp_Scale->getScaleFactor();
-    CGuiApplication::highDpiScreenSupport(scaleFactor);
+    CGuiApplication::highDpiScreenSupport(QString::number(scaleFactor, 'f', 4));
 
     const Qt::KeyboardModifiers km = QGuiApplication::queryKeyboardModifiers();
     const bool shift = km.testFlag(Qt::ShiftModifier);