diff --git a/src/blackgui/guiapplication.cpp b/src/blackgui/guiapplication.cpp
index ca639cd81..9ea3e11e6 100644
--- a/src/blackgui/guiapplication.cpp
+++ b/src/blackgui/guiapplication.cpp
@@ -187,13 +187,16 @@ namespace BlackGui
         if (!mainWindow) { return; }
         if (m_uiSetupCompleted) { return; }
         m_uiSetupCompleted = true;
+
         const QString name(this->getApplicationNameVersionBetaDev());
         mainWindow->setObjectName(QCoreApplication::applicationName());
         mainWindow->setWindowTitle(name);
         mainWindow->setWindowIcon(m_windowIcon);
         mainWindow->setWindowIconText(name);
-        CStyleSheetUtility::setQSysInfoProperties(CGuiApplication::mainApplicationWindow(), true);
-        emit uiObjectTreeReady();
+        CStyleSheetUtility::setQSysInfoProperties(mainWindow, true);
+        CGuiUtility::registerMainApplicationWindow(mainWindow);
+
+        emit this->uiObjectTreeReady();
     }
 
     void CGuiApplication::addWindowFlags(Qt::WindowFlags flags)
diff --git a/src/blackgui/guiutility.cpp b/src/blackgui/guiutility.cpp
index 7d4f973f7..3268f92b4 100644
--- a/src/blackgui/guiutility.cpp
+++ b/src/blackgui/guiutility.cpp
@@ -39,6 +39,8 @@ using namespace BlackMisc;
 
 namespace BlackGui
 {
+    QWidget *CGuiUtility::s_mainApplicationWindow = nullptr;
+
     CEnableForFramelessWindow *CGuiUtility::mainFramelessEnabledApplicationWindow()
     {
         const QWidgetList tlw = topLevelApplicationWidgetsWithName();
@@ -53,7 +55,7 @@ namespace BlackGui
 
     namespace Private
     {
-        QWidget *mainApplicationWindowImpl()
+        QWidget *mainApplicationWindowSearch()
         {
             CEnableForFramelessWindow *mw = CGuiUtility::mainFramelessEnabledApplicationWindow();
             if (mw && mw->getWidget())
@@ -73,15 +75,23 @@ namespace BlackGui
         }
     } // ns
 
+    void CGuiUtility::registerMainApplicationWindow(QWidget *mainWindow)
+    {
+        CGuiUtility::s_mainApplicationWindow = mainWindow;
+    }
+
     QWidget *CGuiUtility::mainApplicationWindow()
     {
-        static QWidget *mw = Private::mainApplicationWindowImpl();
-        return mw;
+        if (!CGuiUtility::s_mainApplicationWindow)
+        {
+            CGuiUtility::s_mainApplicationWindow = Private::mainApplicationWindowSearch();
+        }
+        return CGuiUtility::s_mainApplicationWindow;
     }
 
     bool CGuiUtility::isMainWindowFrameless()
     {
-        const CEnableForFramelessWindow *mw = mainFramelessEnabledApplicationWindow();
+        const CEnableForFramelessWindow *mw = CGuiUtility::mainFramelessEnabledApplicationWindow();
         return (mw && mw->isFrameless());
     }
 
diff --git a/src/blackgui/guiutility.h b/src/blackgui/guiutility.h
index 6ee46149a..ea42c0849 100644
--- a/src/blackgui/guiutility.h
+++ b/src/blackgui/guiutility.h
@@ -41,6 +41,9 @@ namespace BlackGui
         //! Main (frameless enabled) application window
         static CEnableForFramelessWindow *mainFramelessEnabledApplicationWindow();
 
+        //! Register main application window widget if this is known
+        static void registerMainApplicationWindow(QWidget *mainWindow);
+
         //! Main application window widget
         static QWidget *mainApplicationWindow();
 
@@ -131,6 +134,8 @@ namespace BlackGui
     private:
         //! Constructor, use static methods only
         CGuiUtility() {}
+
+        static QWidget *s_mainApplicationWindow;
     };
 } // ns