diff --git a/src/blackgui/enableforframelesswindow.cpp b/src/blackgui/enableforframelesswindow.cpp
index 1e6b663ed..cd06388a7 100644
--- a/src/blackgui/enableforframelesswindow.cpp
+++ b/src/blackgui/enableforframelesswindow.cpp
@@ -28,6 +28,7 @@
 #include <QThread>
 #include <QVariant>
 #include <QWidget>
+#include <QMainWindow>
 #include <QtGlobal>
 
 using namespace BlackMisc;
@@ -86,24 +87,27 @@ namespace BlackGui
 
     CEnableForFramelessWindow::WindowMode CEnableForFramelessWindow::stringToWindowMode(const QString &s)
     {
-        QString ws(s.trimmed().toLower());
+        const QString ws(s.trimmed().toLower());
         if (ws.isEmpty()) { return WindowNormal; }
         if (ws.contains("frameless") || ws.startsWith("f")) { return WindowFrameless; }
         if (ws.contains("tool") || ws.startsWith("t")) { return WindowTool; }
         return WindowNormal;
     }
 
-    QString CEnableForFramelessWindow::windowModeToString(CEnableForFramelessWindow::WindowMode m)
+    const QString &CEnableForFramelessWindow::windowModeToString(CEnableForFramelessWindow::WindowMode m)
     {
+        static const QString n("normal");
+        static const QString f("frameless");
+        static const QString t("tool");
+
         switch (m)
         {
-        case WindowFrameless: return "frameless";
-        case WindowNormal: return "normal";
-        case WindowTool: return "tool";
-        default:
-            break;
+        case WindowFrameless: return f;
+        case WindowNormal:    return n;
+        case WindowTool:      return t;
+        default: break;
         }
-        return "normal";
+        return n;
     }
 
     void CEnableForFramelessWindow::windowFlagsChanged()
@@ -117,13 +121,15 @@ namespace BlackGui
         Q_ASSERT_X(!m_framelessPropertyName.isEmpty(), "CEnableForFramelessWindow::setWindowAttributes", "Missing property name");
 
         bool frameless = (mode == WindowFrameless);
-        // http://stackoverflow.com/questions/18316710/frameless-and-transparent-window-qt5
-        m_widget->setAttribute(Qt::WA_NoSystemBackground, frameless);
 
+        // http://stackoverflow.com/questions/18316710/frameless-and-transparent-window-qt5
         // https://bugreports.qt.io/browse/QTBUG-52206
-        if (CGuiUtility::isTopLevelWidget(m_widget))
+        // UpdateLayeredWindowIndirect failed for ptDst
+        if (m_isMainApplicationWindow && CGuiUtility::isTopLevelWindow(m_widget))
         {
-            m_widget->setAttribute(Qt::WA_TranslucentBackground, frameless);
+            m_widget->setAttribute(Qt::WA_NativeWindow);
+            m_widget->setAttribute(Qt::WA_NoSystemBackground, frameless);
+            m_widget->setAttribute(Qt::WA_TranslucentBackground, frameless); // causing QTBUG-52206
         }
 
         // Qt::WA_PaintOnScreen leads to a warning
diff --git a/src/blackgui/enableforframelesswindow.h b/src/blackgui/enableforframelesswindow.h
index c058e9bb8..6fb00f7ac 100644
--- a/src/blackgui/enableforframelesswindow.h
+++ b/src/blackgui/enableforframelesswindow.h
@@ -51,6 +51,15 @@ namespace BlackGui
         //! \param correspondingWidget     the widget representing the window
         CEnableForFramelessWindow(WindowMode mode, bool isMainApplicationWindow, const char *framelessPropertyname, QWidget *correspondingWidget);
 
+        //! Destructor
+        virtual ~CEnableForFramelessWindow() {}
+
+        //! Copy constructor
+        CEnableForFramelessWindow(const CEnableForFramelessWindow &) = delete ;
+
+        //! Copy assignment operator
+        CEnableForFramelessWindow &operator =(const CEnableForFramelessWindow &) = delete;
+
         //! Window mode
         void setMode(WindowMode mode);
 
@@ -76,7 +85,7 @@ namespace BlackGui
         static WindowMode stringToWindowMode(const QString &s);
 
         //! String to window mode
-        static QString windowModeToString(WindowMode m);
+        static const QString &windowModeToString(WindowMode m);
 
     protected:
         QPoint       m_framelessDragPosition;             //!< position, if moving is handled with frameless window */
diff --git a/src/blackgui/guiutility.cpp b/src/blackgui/guiutility.cpp
index e34461591..1648c51d2 100644
--- a/src/blackgui/guiutility.cpp
+++ b/src/blackgui/guiutility.cpp
@@ -416,9 +416,31 @@ namespace BlackGui
 
     bool CGuiUtility::isTopLevelWidget(QWidget *widget)
     {
+        if (!widget) { return false; }
         return QApplication::topLevelWidgets().contains(widget);
     }
 
+    bool CGuiUtility::isTopLevelWindow(QWidget *widget)
+    {
+        if (!widget) { return false; }
+        if (!widget->isWindow()) { return false; }
+        return QApplication::topLevelWidgets().contains(widget);
+    }
+
+    bool CGuiUtility::isQMainWindow(QWidget *widget)
+    {
+        if (!widget) { return false; }
+        QMainWindow *mw = qobject_cast<QMainWindow *>(widget);
+        return mw;
+    }
+
+    bool CGuiUtility::isDialog(QWidget *widget)
+    {
+        if (!widget) { return false; }
+        QDialog *mw = qobject_cast<QDialog *>(widget);
+        return mw;
+    }
+
     QGraphicsOpacityEffect *CGuiUtility::fadeInWidget(int durationMs, QWidget *widget, double startValue, double endValue)
     {
         // http://stackoverflow.com/questions/19087822/how-to-make-qt-widgets-fade-in-or-fade-out#
@@ -543,8 +565,8 @@ namespace BlackGui
         QWidget *w = CGuiUtility::mainApplicationWidget();
         if (!w) { return; }
         const QSize s = CGuiUtility::desktopSize();
-        const int minW = wRatio * s.width();
-        const int minH = hRatio * s.height();
+        const int minW = qRound(wRatio * s.width());
+        const int minH = qRound(hRatio * s.height());
         w->setMinimumWidth(qMin(minW, w->minimumWidth()));
         w->setMinimumHeight(qMin(minH, w->minimumHeight()));
     }
diff --git a/src/blackgui/guiutility.h b/src/blackgui/guiutility.h
index 9338f8ac7..9536f888d 100644
--- a/src/blackgui/guiutility.h
+++ b/src/blackgui/guiutility.h
@@ -147,6 +147,14 @@ namespace BlackGui
         //! Is top level widget?
         static bool isTopLevelWidget(QWidget *widget);
 
+        //! Is top level window?
+        static bool isTopLevelWindow(QWidget *widget);
+
+        //! Check window type @{
+        static bool isQMainWindow(QWidget *widget);
+        static bool isDialog(QWidget *widget);
+        //! @}
+
         //! Fade in a widget
         static QGraphicsOpacityEffect *fadeInWidget(int durationMs, QWidget *widget, double startValue = 0.0, double endValue = 1.0);