diff --git a/src/Gui/CommandView.cpp b/src/Gui/CommandView.cpp
index cc23a5e4c9..1fa52154d5 100644
--- a/src/Gui/CommandView.cpp
+++ b/src/Gui/CommandView.cpp
@@ -1799,7 +1799,7 @@ void StdViewScreenShot::activated(int iMsg)
                 selFilter = filter.last();
         }
 
-        FileOptionsDialog fd(getMainWindow(), 0);
+        FileOptionsDialog fd(getMainWindow(), Qt::WindowFlags());
         fd.setFileMode(QFileDialog::AnyFile);
         fd.setAcceptMode(QFileDialog::AcceptSave);
         fd.setWindowTitle(QObject::tr("Save picture"));
diff --git a/src/Gui/DemoMode.h b/src/Gui/DemoMode.h
index 1bcf09240c..3c9a76059c 100644
--- a/src/Gui/DemoMode.h
+++ b/src/Gui/DemoMode.h
@@ -44,7 +44,7 @@ class GuiExport DemoMode : public QDialog
     Q_OBJECT
 
 public:
-    DemoMode(QWidget* parent = 0, Qt::WindowFlags fl = 0);
+    DemoMode(QWidget* parent = 0, Qt::WindowFlags fl = Qt::WindowFlags());
     ~DemoMode();
 
     void accept();
diff --git a/src/Gui/DlgActivateWindowImp.h b/src/Gui/DlgActivateWindowImp.h
index 6017394a31..96eedd266b 100644
--- a/src/Gui/DlgActivateWindowImp.h
+++ b/src/Gui/DlgActivateWindowImp.h
@@ -40,7 +40,7 @@ class DlgActivateWindowImp : public QDialog
     Q_OBJECT
 
 public:
-    DlgActivateWindowImp(QWidget* parent = 0, Qt::WindowFlags fl = 0);
+    DlgActivateWindowImp(QWidget* parent = 0, Qt::WindowFlags fl = Qt::WindowFlags());
     ~DlgActivateWindowImp();
 
 protected:
diff --git a/src/Gui/DlgCustomizeImp.h b/src/Gui/DlgCustomizeImp.h
index e416b27c0f..aa1403cffa 100644
--- a/src/Gui/DlgCustomizeImp.h
+++ b/src/Gui/DlgCustomizeImp.h
@@ -51,7 +51,7 @@ class DlgCustomizeImp : public QDialog
     Q_OBJECT
 
 public:
-    DlgCustomizeImp(QWidget* parent = 0, Qt::WindowFlags fl = 0);
+    DlgCustomizeImp(QWidget* parent = 0, Qt::WindowFlags fl = Qt::WindowFlags());
     ~DlgCustomizeImp();
 
     static void addPage(const char* className);
diff --git a/src/Gui/DlgDisplayPropertiesImp.h b/src/Gui/DlgDisplayPropertiesImp.h
index 1b82e8c043..78c607604f 100644
--- a/src/Gui/DlgDisplayPropertiesImp.h
+++ b/src/Gui/DlgDisplayPropertiesImp.h
@@ -56,7 +56,7 @@ class DlgDisplayPropertiesImp : public QDialog,
     Q_OBJECT
 
 public:
-    DlgDisplayPropertiesImp(bool floating, QWidget* parent = nullptr, Qt::WindowFlags fl = 0);
+    DlgDisplayPropertiesImp(bool floating, QWidget* parent = nullptr, Qt::WindowFlags fl = Qt::WindowFlags());
     ~DlgDisplayPropertiesImp();
     /// Observer message from the Selection
     void OnChange(Gui::SelectionSingleton::SubjectType &rCaller,
diff --git a/src/Gui/DlgEditFileIncludePropertyExternal.h b/src/Gui/DlgEditFileIncludePropertyExternal.h
index 4823682839..2cf6b598dc 100644
--- a/src/Gui/DlgEditFileIncludePropertyExternal.h
+++ b/src/Gui/DlgEditFileIncludePropertyExternal.h
@@ -39,7 +39,7 @@ class GuiExport DlgEditFileIncludePropertyExternal : public DlgRunExternal
     Q_OBJECT
 
 public:
-    DlgEditFileIncludePropertyExternal( App::PropertyFileIncluded& Prop, QWidget* parent = 0, Qt::WindowFlags fl = 0 );
+    DlgEditFileIncludePropertyExternal( App::PropertyFileIncluded& Prop, QWidget* parent = 0, Qt::WindowFlags fl = Qt::WindowFlags() );
     virtual ~DlgEditFileIncludePropertyExternal();
 
     int Do(void);
diff --git a/src/Gui/DlgMacroExecuteImp.h b/src/Gui/DlgMacroExecuteImp.h
index 8204aa2127..751b3f04ca 100644
--- a/src/Gui/DlgMacroExecuteImp.h
+++ b/src/Gui/DlgMacroExecuteImp.h
@@ -44,7 +44,7 @@ class DlgMacroExecuteImp : public QDialog, public Gui::WindowParameter
     Q_OBJECT
 
 public:
-    DlgMacroExecuteImp( QWidget* parent = 0, Qt::WindowFlags fl = 0 );
+    DlgMacroExecuteImp( QWidget* parent = 0, Qt::WindowFlags fl =  Qt::WindowFlags() );
     ~DlgMacroExecuteImp();
 
     void accept();
diff --git a/src/Gui/DlgMacroRecordImp.h b/src/Gui/DlgMacroRecordImp.h
index 844cfa7afb..243a61aead 100644
--- a/src/Gui/DlgMacroRecordImp.h
+++ b/src/Gui/DlgMacroRecordImp.h
@@ -43,7 +43,7 @@ class DlgMacroRecordImp : public QDialog, public Gui::WindowParameter
     Q_OBJECT
 
 public:
-    DlgMacroRecordImp( QWidget* parent = 0, Qt::WindowFlags fl = 0 );
+    DlgMacroRecordImp( QWidget* parent = 0, Qt::WindowFlags fl = Qt::WindowFlags() );
     virtual ~DlgMacroRecordImp();
 
 protected Q_SLOTS:
diff --git a/src/Gui/DlgMaterialPropertiesImp.h b/src/Gui/DlgMaterialPropertiesImp.h
index e8c389eace..e91103fb08 100644
--- a/src/Gui/DlgMaterialPropertiesImp.h
+++ b/src/Gui/DlgMaterialPropertiesImp.h
@@ -39,7 +39,7 @@ class DlgMaterialPropertiesImp : public QDialog
     Q_OBJECT
 
 public:
-    DlgMaterialPropertiesImp(const std::string& mat, QWidget* parent = 0, Qt::WindowFlags fl = 0);
+    DlgMaterialPropertiesImp(const std::string& mat, QWidget* parent = 0, Qt::WindowFlags fl = Qt::WindowFlags());
     ~DlgMaterialPropertiesImp();
     void setViewProviders(const std::vector<Gui::ViewProvider*>&);
     QColor diffuseColor() const;
diff --git a/src/Gui/DlgObjectSelection.h b/src/Gui/DlgObjectSelection.h
index b8c22f3ff0..f555546b4d 100644
--- a/src/Gui/DlgObjectSelection.h
+++ b/src/Gui/DlgObjectSelection.h
@@ -33,7 +33,7 @@ class GuiExport DlgObjectSelection : public QDialog
 
 public:
     DlgObjectSelection(const std::vector<App::DocumentObject*> &objs, 
-            QWidget* parent = 0, Qt::WindowFlags fl = 0);
+            QWidget* parent = 0, Qt::WindowFlags fl = Qt::WindowFlags());
     ~DlgObjectSelection();
 
     std::vector<App::DocumentObject*> getSelections() const;
diff --git a/src/Gui/DlgParameterImp.h b/src/Gui/DlgParameterImp.h
index c19d9ce194..9e47758dd2 100644
--- a/src/Gui/DlgParameterImp.h
+++ b/src/Gui/DlgParameterImp.h
@@ -46,7 +46,7 @@ class GuiExport DlgParameterImp : public QDialog
     Q_OBJECT
 
 public:
-    DlgParameterImp( QWidget* parent = 0, Qt::WindowFlags fl = 0 );
+    DlgParameterImp( QWidget* parent = 0, Qt::WindowFlags fl = Qt::WindowFlags() );
     ~DlgParameterImp();
 
     void accept();
diff --git a/src/Gui/DlgPreferencesImp.h b/src/Gui/DlgPreferencesImp.h
index 6594669ab6..356afab5a1 100644
--- a/src/Gui/DlgPreferencesImp.h
+++ b/src/Gui/DlgPreferencesImp.h
@@ -112,7 +112,7 @@ public:
     static void addPage(const std::string& className, const std::string& group);
     static void removePage(const std::string& className, const std::string& group);
 
-    DlgPreferencesImp(QWidget* parent = 0, Qt::WindowFlags fl = 0);
+    DlgPreferencesImp(QWidget* parent = 0, Qt::WindowFlags fl = Qt::WindowFlags());
     ~DlgPreferencesImp();
 
     void accept();
diff --git a/src/Gui/DlgProjectInformationImp.h b/src/Gui/DlgProjectInformationImp.h
index 452121bdb4..7ef387f12f 100644
--- a/src/Gui/DlgProjectInformationImp.h
+++ b/src/Gui/DlgProjectInformationImp.h
@@ -40,7 +40,7 @@ class DlgProjectInformationImp : public QDialog
     Q_OBJECT
 
 public:
-    DlgProjectInformationImp(App::Document* doc, QWidget* parent = 0, Qt::WindowFlags fl = 0);
+    DlgProjectInformationImp(App::Document* doc, QWidget* parent = 0, Qt::WindowFlags fl = Qt::WindowFlags());
     ~DlgProjectInformationImp();
     void accept();
 
diff --git a/src/Gui/DlgProjectUtility.h b/src/Gui/DlgProjectUtility.h
index 6721b8f776..9363b75b0f 100644
--- a/src/Gui/DlgProjectUtility.h
+++ b/src/Gui/DlgProjectUtility.h
@@ -35,7 +35,7 @@ class DlgProjectUtility : public QDialog
     Q_OBJECT
 
 public:
-    DlgProjectUtility(QWidget* parent = 0, Qt::WindowFlags fl = 0);
+    DlgProjectUtility(QWidget* parent = 0, Qt::WindowFlags fl = Qt::WindowFlags());
     ~DlgProjectUtility();
 
 private Q_SLOTS:
diff --git a/src/Gui/DlgRunExternal.h b/src/Gui/DlgRunExternal.h
index 9b2a7617fa..65693858a2 100644
--- a/src/Gui/DlgRunExternal.h
+++ b/src/Gui/DlgRunExternal.h
@@ -41,7 +41,7 @@ class GuiExport DlgRunExternal : public QDialog
     Q_OBJECT
 
 public:
-    DlgRunExternal(QWidget* parent = 0, Qt::WindowFlags fl = 0);
+    DlgRunExternal(QWidget* parent = 0, Qt::WindowFlags fl = Qt::WindowFlags());
     virtual ~DlgRunExternal();
 
     int Do(void);
diff --git a/src/Gui/DlgSettingsColorGradientImp.h b/src/Gui/DlgSettingsColorGradientImp.h
index b6f2a8a3dd..986ab3d7bf 100644
--- a/src/Gui/DlgSettingsColorGradientImp.h
+++ b/src/Gui/DlgSettingsColorGradientImp.h
@@ -44,7 +44,7 @@ class DlgSettingsColorGradientImp : public QDialog
     Q_OBJECT
 
 public:
-    DlgSettingsColorGradientImp( QWidget* parent = 0, Qt::WindowFlags fl = 0 );
+    DlgSettingsColorGradientImp( QWidget* parent = 0, Qt::WindowFlags fl = Qt::WindowFlags() );
     ~DlgSettingsColorGradientImp();
 
     void accept();
diff --git a/src/Gui/DlgUnitsCalculatorImp.h b/src/Gui/DlgUnitsCalculatorImp.h
index 00f0d2bfc0..0e1ddd5607 100644
--- a/src/Gui/DlgUnitsCalculatorImp.h
+++ b/src/Gui/DlgUnitsCalculatorImp.h
@@ -42,7 +42,7 @@ class DlgUnitsCalculator : public QDialog
     Q_OBJECT
 
 public:
-    DlgUnitsCalculator(QWidget* parent = 0, Qt::WindowFlags fl = 0);
+    DlgUnitsCalculator(QWidget* parent = 0, Qt::WindowFlags fl = Qt::WindowFlags());
     ~DlgUnitsCalculator();
 
 protected:
diff --git a/src/Gui/DocumentModel.cpp b/src/Gui/DocumentModel.cpp
index b1692424c3..a43e9a07bf 100644
--- a/src/Gui/DocumentModel.cpp
+++ b/src/Gui/DocumentModel.cpp
@@ -628,7 +628,7 @@ Qt::ItemFlags DocumentModel::flags(const QModelIndex &index) const
     //    return Qt::ItemIsEnabled;
     //return QAbstractItemModel::flags(index);
     if (!index.isValid())
-        return 0;
+        return Qt::ItemFlags();
     return static_cast<DocumentModelIndex*>(index.internalPointer())->flags();
 }
 
diff --git a/src/Gui/EditorView.cpp b/src/Gui/EditorView.cpp
index 27e9127263..eb13f0a7b3 100644
--- a/src/Gui/EditorView.cpp
+++ b/src/Gui/EditorView.cpp
@@ -79,7 +79,7 @@ public:
  *  name 'name'.
  */
 EditorView::EditorView(QPlainTextEdit* editor, QWidget* parent)
-    : MDIView(0,parent,0), WindowParameter( "Editor" )
+    : MDIView(0,parent,Qt::WindowFlags()), WindowParameter( "Editor" )
 {
     d = new EditorViewP;
     d->lock = false;
diff --git a/src/Gui/FileDialog.h b/src/Gui/FileDialog.h
index 61dd6ecf2c..c5f1fcef20 100644
--- a/src/Gui/FileDialog.h
+++ b/src/Gui/FileDialog.h
@@ -49,13 +49,13 @@ class GuiExport FileDialog : public QFileDialog
 
 public:
     static QString getOpenFileName( QWidget * parent = 0, const QString & caption = QString(), const QString & dir = QString(), 
-                                    const QString & filter = QString(), QString * selectedFilter = 0, Options options = 0 );
+                                    const QString & filter = QString(), QString * selectedFilter = 0, Options options = Options() );
     static QString getSaveFileName( QWidget * parent = 0, const QString & caption = QString(), const QString & dir = QString(), 
-                                    const QString & filter = QString(), QString * selectedFilter = 0, Options options = 0 );
+                                    const QString & filter = QString(), QString * selectedFilter = 0, Options options = Options() );
     static QString getExistingDirectory( QWidget * parent = 0, const QString & caption = QString(), const QString & dir = QString(), 
                                          Options options = ShowDirsOnly );
     static QStringList getOpenFileNames( QWidget * parent = 0, const QString & caption = QString(), const QString & dir = QString(),
-                                         const QString & filter = QString(), QString * selectedFilter = 0, Options options = 0 );
+                                         const QString & filter = QString(), QString * selectedFilter = 0, Options options = Options() );
 
     /*! Return the last directory a file was read from or saved to. */
     static QString getWorkingDirectory();
diff --git a/src/Gui/InputVector.h b/src/Gui/InputVector.h
index 2a91b4836c..45af70d00a 100644
--- a/src/Gui/InputVector.h
+++ b/src/Gui/InputVector.h
@@ -83,7 +83,7 @@ class GuiExport LocationDialog : public QDialog
     Q_OBJECT
 
 protected:
-    LocationDialog(QWidget* parent = 0, Qt::WindowFlags fl = 0);
+    LocationDialog(QWidget* parent = 0, Qt::WindowFlags fl = Qt::WindowFlags());
     virtual ~LocationDialog();
 
 protected:
@@ -116,7 +116,7 @@ template <class Ui>
 class LocationDialogUi : public LocationDialog, public Ui
 {
 public:
-    LocationDialogUi(QWidget* parent = 0, Qt::WindowFlags fl = 0)  : LocationDialog(parent, fl)
+    LocationDialogUi(QWidget* parent = 0, Qt::WindowFlags fl = Qt::WindowFlags())  : LocationDialog(parent, fl)
     {
         this->setupUi(this);
         this->retranslate();
@@ -366,7 +366,7 @@ template <class Ui>
 class LocationDialogImp : public LocationDialog
 {
 public:
-    LocationDialogImp(QWidget* parent = 0, Qt::WindowFlags fl = 0)
+    LocationDialogImp(QWidget* parent = 0, Qt::WindowFlags fl = Qt::WindowFlags())
       : LocationDialog(parent, fl), ui(this)
     {
     }
@@ -556,7 +556,7 @@ class GuiExport LocationDialogUiImp : public LocationDialog
 {
 public:
     template<class T>
-    LocationDialogUiImp(T* t, QWidget* parent = 0, Qt::WindowFlags fl = 0)
+    LocationDialogUiImp(T* t, QWidget* parent = 0, Qt::WindowFlags fl =  Qt::WindowFlags())
       : LocationDialog(parent, fl), ui(new LocationImpUi<T>(t))
     {
         std::shared_ptr<T> uit = boost::any_cast< std::shared_ptr<T> >(ui->get());
diff --git a/src/Gui/MDIView.h b/src/Gui/MDIView.h
index 87c6e835d7..c33f9a336b 100644
--- a/src/Gui/MDIView.h
+++ b/src/Gui/MDIView.h
@@ -62,7 +62,7 @@ public:
      * the view will attach to the active document. Be aware, there isn't
      * always an active document.
      */
-    MDIView(Gui::Document* pcDocument, QWidget* parent, Qt::WindowFlags wflags=0);
+    MDIView(Gui::Document* pcDocument, QWidget* parent, Qt::WindowFlags wflags=Qt::WindowFlags());
     /** View destructor
      * Detach the view from the document, if attached.
      */
diff --git a/src/Gui/ManualAlignment.cpp b/src/Gui/ManualAlignment.cpp
index cf280bf8f8..34dfd5111f 100644
--- a/src/Gui/ManualAlignment.cpp
+++ b/src/Gui/ManualAlignment.cpp
@@ -369,7 +369,7 @@ class AlignmentView : public Gui::AbstractSplitView
 public:
     QLabel* myLabel;
 
-    AlignmentView(Gui::Document* pcDocument, QWidget* parent, Qt::WindowFlags wflags=0)
+    AlignmentView(Gui::Document* pcDocument, QWidget* parent, Qt::WindowFlags wflags=Qt::WindowFlags())
         : AbstractSplitView(pcDocument, parent, wflags)
     {
         //anti-aliasing settings
diff --git a/src/Gui/Placement.h b/src/Gui/Placement.h
index fb5a6b0075..7437bd5d02 100644
--- a/src/Gui/Placement.h
+++ b/src/Gui/Placement.h
@@ -45,7 +45,7 @@ class GuiExport Placement : public Gui::LocationDialog
     Q_OBJECT
 
 public:
-    Placement(QWidget* parent = 0, Qt::WindowFlags fl = 0);
+    Placement(QWidget* parent = 0, Qt::WindowFlags fl = Qt::WindowFlags());
     ~Placement();
     void accept();
     void reject();
@@ -116,7 +116,7 @@ class GuiExport DockablePlacement : public Placement
     Q_OBJECT
 
 public:
-    DockablePlacement(QWidget* parent = 0, Qt::WindowFlags fl = 0);
+    DockablePlacement(QWidget* parent = 0, Qt::WindowFlags fl = Qt::WindowFlags());
     ~DockablePlacement();
 
     void accept();
diff --git a/src/Gui/QSint/actionpanel/actionbox.h b/src/Gui/QSint/actionpanel/actionbox.h
index 0b599349dc..bd94ee0780 100644
--- a/src/Gui/QSint/actionpanel/actionbox.h
+++ b/src/Gui/QSint/actionpanel/actionbox.h
@@ -182,7 +182,7 @@ public:
     void setIcon(const QPixmap & icon);
     /** Returns icon of the ActionBox.
       */
-    inline const QPixmap* icon() const { return iconLabel->pixmap(); }
+    inline QPixmap icon() { return iconLabel->pixmap(Qt::ReturnByValue); }
 
     /** Returns header item of the ActionBox.
       */
diff --git a/src/Gui/QSint/actionpanel/taskheader_p.cpp b/src/Gui/QSint/actionpanel/taskheader_p.cpp
index 42f18b9dc8..63c9e0d19c 100644
--- a/src/Gui/QSint/actionpanel/taskheader_p.cpp
+++ b/src/Gui/QSint/actionpanel/taskheader_p.cpp
@@ -264,7 +264,7 @@ void TaskHeader::keyPressEvent ( QKeyEvent * event )
   {
     case Qt::Key_Down:
     {
-      QKeyEvent ke(QEvent::KeyPress, Qt::Key_Tab, 0);
+      QKeyEvent ke(QEvent::KeyPress, Qt::Key_Tab,0 );
       QApplication::sendEvent(this, &ke);
       return;
     }
diff --git a/src/Gui/Quarter/QuarterWidget.cpp b/src/Gui/Quarter/QuarterWidget.cpp
index e8ba92fc96..75551987ea 100644
--- a/src/Gui/Quarter/QuarterWidget.cpp
+++ b/src/Gui/Quarter/QuarterWidget.cpp
@@ -154,7 +154,7 @@ class CustomGLWidget : public QOpenGLWidget {
 public:
     QSurfaceFormat myFormat;
 
-    CustomGLWidget(const QSurfaceFormat& format, QWidget* parent = 0, const QOpenGLWidget* shareWidget = 0, Qt::WindowFlags f = 0)
+    CustomGLWidget(const QSurfaceFormat& format, QWidget* parent = 0, const QOpenGLWidget* shareWidget = 0, Qt::WindowFlags f = Qt::WindowFlags())
      : QOpenGLWidget(parent, f), myFormat(format)
     {
         Q_UNUSED(shareWidget);
diff --git a/src/Gui/Quarter/QuarterWidget.h b/src/Gui/Quarter/QuarterWidget.h
index a124193885..d69bf2c5b6 100644
--- a/src/Gui/Quarter/QuarterWidget.h
+++ b/src/Gui/Quarter/QuarterWidget.h
@@ -81,9 +81,9 @@ class QUARTER_DLL_API QuarterWidget : public QGraphicsView {
 
 
 public:
-  explicit QuarterWidget(QWidget * parent = 0, const QtGLWidget * sharewidget = 0, Qt::WindowFlags f = 0);
-  explicit QuarterWidget(QtGLContext * context, QWidget * parent = 0, const QtGLWidget * sharewidget = 0, Qt::WindowFlags f = 0);
-  explicit QuarterWidget(const QtGLFormat & format, QWidget * parent = 0, const QtGLWidget * shareWidget = 0, Qt::WindowFlags f = 0);
+  explicit QuarterWidget(QWidget * parent = 0, const QtGLWidget * sharewidget = 0, Qt::WindowFlags f = Qt::WindowFlags());
+  explicit QuarterWidget(QtGLContext * context, QWidget * parent = 0, const QtGLWidget * sharewidget = 0, Qt::WindowFlags f = Qt::WindowFlags());
+  explicit QuarterWidget(const QtGLFormat & format, QWidget * parent = 0, const QtGLWidget * shareWidget = 0, Qt::WindowFlags f = Qt::WindowFlags());
   virtual ~QuarterWidget();
 
   enum TransparencyType {
diff --git a/src/Gui/Quarter/SoQTQuarterAdaptor.h b/src/Gui/Quarter/SoQTQuarterAdaptor.h
index 9d3fab2d4b..84956532d4 100644
--- a/src/Gui/Quarter/SoQTQuarterAdaptor.h
+++ b/src/Gui/Quarter/SoQTQuarterAdaptor.h
@@ -47,9 +47,9 @@ typedef void SoQTQuarterAdaptorCB(void* data, SoQTQuarterAdaptor* viewer);
 class QUARTER_DLL_API SoQTQuarterAdaptor :  public QuarterWidget {
 
 public:
-    explicit SoQTQuarterAdaptor(QWidget* parent = 0, const QtGLWidget* sharewidget = 0, Qt::WindowFlags f = 0);
-    explicit SoQTQuarterAdaptor(const QtGLFormat& format, QWidget* parent = 0, const QtGLWidget* shareWidget = 0, Qt::WindowFlags f = 0);
-    explicit SoQTQuarterAdaptor(QtGLContext* context, QWidget* parent = 0, const QtGLWidget* sharewidget = 0, Qt::WindowFlags f = 0);
+    explicit SoQTQuarterAdaptor(QWidget* parent = 0, const QtGLWidget* sharewidget = 0, Qt::WindowFlags f = Qt::WindowFlags());
+    explicit SoQTQuarterAdaptor(const QtGLFormat& format, QWidget* parent = 0, const QtGLWidget* shareWidget = 0, Qt::WindowFlags f = Qt::WindowFlags());
+    explicit SoQTQuarterAdaptor(QtGLContext* context, QWidget* parent = 0, const QtGLWidget* sharewidget = 0, Qt::WindowFlags f = Qt::WindowFlags());
     virtual ~SoQTQuarterAdaptor();
 
     //the functions available in soqtviewer but missing in quarter
diff --git a/src/Gui/SceneInspector.h b/src/Gui/SceneInspector.h
index 48d90d9693..52661ced76 100644
--- a/src/Gui/SceneInspector.h
+++ b/src/Gui/SceneInspector.h
@@ -71,7 +71,7 @@ class DlgInspector : public QDialog
     Q_OBJECT
 
 public:
-    DlgInspector(QWidget* parent = 0, Qt::WindowFlags fl = 0);
+    DlgInspector(QWidget* parent = 0, Qt::WindowFlags fl = Qt::WindowFlags());
     ~DlgInspector();
 
     void setDocument(Gui::Document* doc);
diff --git a/src/Gui/Splashscreen.cpp b/src/Gui/Splashscreen.cpp
index 66efe4df49..fda58b3461 100644
--- a/src/Gui/Splashscreen.cpp
+++ b/src/Gui/Splashscreen.cpp
@@ -826,7 +826,7 @@ void AboutDialog::on_copyButton_clicked()
 /* TRANSLATOR Gui::LicenseView */
 
 LicenseView::LicenseView(QWidget* parent)
-    : MDIView(0,parent,0)
+    : MDIView(0,parent,Qt::WindowFlags())
 {
     browser = new QTextBrowser(this);
     browser->setOpenExternalLinks(true);
diff --git a/src/Gui/Splashscreen.h b/src/Gui/Splashscreen.h
index 6b2142feca..0baa568c1e 100644
--- a/src/Gui/Splashscreen.h
+++ b/src/Gui/Splashscreen.h
@@ -42,7 +42,7 @@ class SplashScreen : public QSplashScreen
     Q_OBJECT
 
 public:
-    SplashScreen(  const QPixmap & pixmap = QPixmap ( ), Qt::WindowFlags f = 0 );
+    SplashScreen(  const QPixmap & pixmap = QPixmap ( ), Qt::WindowFlags f = Qt::WindowFlags() );
     ~SplashScreen();
 
 protected:
diff --git a/src/Gui/SplitView3DInventor.h b/src/Gui/SplitView3DInventor.h
index 2b28a6e035..bbbdd6d3fd 100644
--- a/src/Gui/SplitView3DInventor.h
+++ b/src/Gui/SplitView3DInventor.h
@@ -42,7 +42,7 @@ class GuiExport AbstractSplitView : public MDIView, public ParameterGrp::Observe
     TYPESYSTEM_HEADER();
 
 public:
-    AbstractSplitView(Gui::Document* pcDocument, QWidget* parent, Qt::WindowFlags wflags=0);
+    AbstractSplitView(Gui::Document* pcDocument, QWidget* parent, Qt::WindowFlags wflags=Qt::WindowFlags());
     ~AbstractSplitView();
 
     virtual const char *getName(void) const;
@@ -109,7 +109,7 @@ class GuiExport SplitView3DInventor : public AbstractSplitView
     TYPESYSTEM_HEADER();
 
 public:
-    SplitView3DInventor(int views, Gui::Document* pcDocument, QWidget* parent, Qt::WindowFlags wflags=0);
+    SplitView3DInventor(int views, Gui::Document* pcDocument, QWidget* parent, Qt::WindowFlags wflags=Qt::WindowFlags());
     ~SplitView3DInventor();
 };
 
diff --git a/src/Gui/TextureMapping.h b/src/Gui/TextureMapping.h
index f7ff6ef141..787215465b 100644
--- a/src/Gui/TextureMapping.h
+++ b/src/Gui/TextureMapping.h
@@ -39,7 +39,7 @@ class GuiExport TextureMapping : public QDialog
     Q_OBJECT
 
 public:
-    TextureMapping(QWidget* parent = 0, Qt::WindowFlags fl = 0);
+    TextureMapping(QWidget* parent = 0, Qt::WindowFlags fl = Qt::WindowFlags());
     ~TextureMapping();
     void accept();
     void reject();
diff --git a/src/Gui/Transform.h b/src/Gui/Transform.h
index 3c1ef3090e..a76d1e7d56 100644
--- a/src/Gui/Transform.h
+++ b/src/Gui/Transform.h
@@ -71,7 +71,7 @@ class GuiExport Transform : public Gui::LocationDialog
     Q_OBJECT
 
 public:
-    Transform(QWidget* parent = 0, Qt::WindowFlags fl = 0);
+    Transform(QWidget* parent = 0, Qt::WindowFlags fl = Qt::WindowFlags());
     ~Transform();
     void accept();
     void reject();
diff --git a/src/Gui/View3DInventor.h b/src/Gui/View3DInventor.h
index 76534a2851..106b38190e 100644
--- a/src/Gui/View3DInventor.h
+++ b/src/Gui/View3DInventor.h
@@ -68,7 +68,7 @@ class GuiExport View3DInventor : public MDIView, public ParameterGrp::ObserverTy
     TYPESYSTEM_HEADER();
 
 public:
-    View3DInventor(Gui::Document* pcDocument, QWidget* parent, const QtGLWidget* sharewidget = 0, Qt::WindowFlags wflags=0);
+    View3DInventor(Gui::Document* pcDocument, QWidget* parent, const QtGLWidget* sharewidget = 0, Qt::WindowFlags wflags=Qt::WindowFlags());
     ~View3DInventor();
 
     /// Message handler
diff --git a/src/Gui/Widgets.h b/src/Gui/Widgets.h
index c2aed4189f..2d0a80147b 100644
--- a/src/Gui/Widgets.h
+++ b/src/Gui/Widgets.h
@@ -179,7 +179,7 @@ class GuiExport CheckListDialog : public QDialog
   Q_OBJECT
 
 public:
-  CheckListDialog( QWidget* parent = 0, Qt::WindowFlags fl = 0 );
+  CheckListDialog( QWidget* parent = 0, Qt::WindowFlags fl = Qt::WindowFlags() );
   ~CheckListDialog();
 
   void setCheckableItems( const QStringList& items );
@@ -260,7 +260,7 @@ class GuiExport UrlLabel : public QLabel
   Q_PROPERTY( QString  url    READ url   WRITE setUrl)
 
 public:
-  UrlLabel ( QWidget * parent = 0, Qt::WindowFlags f = 0 );
+  UrlLabel ( QWidget * parent = 0, Qt::WindowFlags f = Qt::WindowFlags() );
   virtual ~UrlLabel();
 
   QString url() const;
diff --git a/src/Mod/Drawing/Gui/DrawingView.cpp b/src/Mod/Drawing/Gui/DrawingView.cpp
index d46ed8c55b..5e8cc3de4b 100644
--- a/src/Mod/Drawing/Gui/DrawingView.cpp
+++ b/src/Mod/Drawing/Gui/DrawingView.cpp
@@ -463,7 +463,7 @@ void DrawingView::onRelabel(Gui::Document *pDoc)
 
 void DrawingView::printPdf()
 {
-    Gui::FileOptionsDialog dlg(this, 0);
+    Gui::FileOptionsDialog dlg(this, Qt::WindowFlags());
     dlg.setFileMode(QFileDialog::AnyFile);
     dlg.setAcceptMode(QFileDialog::AcceptSave);
     dlg.setWindowTitle(tr("Export PDF"));
diff --git a/src/Mod/Image/Gui/OpenGLImageBox.h b/src/Mod/Image/Gui/OpenGLImageBox.h
index aa5f29fbee..7959b36300 100644
--- a/src/Mod/Image/Gui/OpenGLImageBox.h
+++ b/src/Mod/Image/Gui/OpenGLImageBox.h
@@ -37,7 +37,7 @@ class ImageGuiExport GLImageBox : public QOpenGLWidget
 
 public:
 
-    GLImageBox(QWidget * parent = 0, Qt::WindowFlags f = 0);
+    GLImageBox(QWidget * parent = 0, Qt::WindowFlags f = Qt::WindowFlags());
     ~GLImageBox();
 
     Image::ImageBase *getImageBasePtr() { return &_image; }
diff --git a/src/Mod/Inspection/Gui/VisualInspection.h b/src/Mod/Inspection/Gui/VisualInspection.h
index 9c6716c5f0..fc4d6d9e36 100644
--- a/src/Mod/Inspection/Gui/VisualInspection.h
+++ b/src/Mod/Inspection/Gui/VisualInspection.h
@@ -37,7 +37,7 @@ class VisualInspection : public QDialog
     Q_OBJECT
 
 public:
-    VisualInspection(QWidget* parent = 0, Qt::WindowFlags fl = 0);
+    VisualInspection(QWidget* parent = 0, Qt::WindowFlags fl = Qt::WindowFlags());
   ~ VisualInspection();
 
     void accept();
diff --git a/src/Mod/Mesh/Gui/DlgDecimating.h b/src/Mod/Mesh/Gui/DlgDecimating.h
index 47fdc15ce8..6af1fa7acd 100644
--- a/src/Mod/Mesh/Gui/DlgDecimating.h
+++ b/src/Mod/Mesh/Gui/DlgDecimating.h
@@ -36,7 +36,7 @@ class DlgDecimating : public QWidget
     Q_OBJECT
 
 public:
-    DlgDecimating(QWidget* parent = 0, Qt::WindowFlags fl = 0);
+    DlgDecimating(QWidget* parent = 0, Qt::WindowFlags fl = Qt::WindowFlags());
     ~DlgDecimating();
     void setNumberOfTriangles(int);
     double tolerance() const;
diff --git a/src/Mod/Mesh/Gui/DlgEvaluateMeshImp.h b/src/Mod/Mesh/Gui/DlgEvaluateMeshImp.h
index a553747946..e5cf94472f 100644
--- a/src/Mod/Mesh/Gui/DlgEvaluateMeshImp.h
+++ b/src/Mod/Mesh/Gui/DlgEvaluateMeshImp.h
@@ -68,7 +68,7 @@ class DlgEvaluateMeshImp : public QDialog, public App::DocumentObserver
     Q_OBJECT
 
 public:
-    DlgEvaluateMeshImp(QWidget* parent = 0, Qt::WindowFlags fl = 0);
+    DlgEvaluateMeshImp(QWidget* parent = 0, Qt::WindowFlags fl = Qt::WindowFlags());
     ~DlgEvaluateMeshImp();
 
     void setMesh(Mesh::Feature*);
@@ -146,7 +146,7 @@ class DockEvaluateMeshImp : public DlgEvaluateMeshImp
     Q_OBJECT
 
 protected:
-    DockEvaluateMeshImp( QWidget* parent = 0, Qt::WindowFlags fl = 0 );
+    DockEvaluateMeshImp( QWidget* parent = 0, Qt::WindowFlags fl = Qt::WindowFlags() );
     ~DockEvaluateMeshImp();
     void closeEvent(QCloseEvent* e);
 
diff --git a/src/Mod/Mesh/Gui/DlgEvaluateSettings.h b/src/Mod/Mesh/Gui/DlgEvaluateSettings.h
index 3fa8c00c51..4928cbdf17 100644
--- a/src/Mod/Mesh/Gui/DlgEvaluateSettings.h
+++ b/src/Mod/Mesh/Gui/DlgEvaluateSettings.h
@@ -38,7 +38,7 @@ class DlgEvaluateSettings : public QDialog
     Q_OBJECT
 
 public:
-    DlgEvaluateSettings(QWidget* parent = 0, Qt::WindowFlags fl = 0);
+    DlgEvaluateSettings(QWidget* parent = 0, Qt::WindowFlags fl = Qt::WindowFlags());
     ~DlgEvaluateSettings();
 
     void setNonmanifoldPointsChecked(bool);
diff --git a/src/Mod/Mesh/Gui/DlgRegularSolidImp.h b/src/Mod/Mesh/Gui/DlgRegularSolidImp.h
index ab7f4a2237..b67b5baba5 100644
--- a/src/Mod/Mesh/Gui/DlgRegularSolidImp.h
+++ b/src/Mod/Mesh/Gui/DlgRegularSolidImp.h
@@ -34,7 +34,7 @@ class DlgRegularSolidImp : public QDialog
     Q_OBJECT
 
 public:
-    DlgRegularSolidImp(QWidget* parent = 0, Qt::WindowFlags fl = 0);
+    DlgRegularSolidImp(QWidget* parent = 0, Qt::WindowFlags fl = Qt::WindowFlags());
     ~DlgRegularSolidImp();
 
 public Q_SLOTS:
diff --git a/src/Mod/Mesh/Gui/DlgSmoothing.h b/src/Mod/Mesh/Gui/DlgSmoothing.h
index 7b035e5475..49b8047cad 100644
--- a/src/Mod/Mesh/Gui/DlgSmoothing.h
+++ b/src/Mod/Mesh/Gui/DlgSmoothing.h
@@ -73,7 +73,7 @@ class MeshGuiExport SmoothingDialog : public QDialog
     Q_OBJECT
 
 public:
-    SmoothingDialog(QWidget* parent = 0, Qt::WindowFlags fl = 0);
+    SmoothingDialog(QWidget* parent = 0, Qt::WindowFlags fl = Qt::WindowFlags());
     ~SmoothingDialog();
 
     int iterations() const
diff --git a/src/Mod/Mesh/Gui/RemeshGmsh.h b/src/Mod/Mesh/Gui/RemeshGmsh.h
index b2348379c0..82fda38c69 100644
--- a/src/Mod/Mesh/Gui/RemeshGmsh.h
+++ b/src/Mod/Mesh/Gui/RemeshGmsh.h
@@ -52,7 +52,7 @@ class MeshGuiExport GmshWidget : public QWidget
     Q_OBJECT
 
 public:
-    GmshWidget(QWidget* parent = 0, Qt::WindowFlags fl = 0);
+    GmshWidget(QWidget* parent = 0, Qt::WindowFlags fl = Qt::WindowFlags());
     ~GmshWidget();
     void accept();
     void reject();
@@ -90,7 +90,7 @@ class MeshGuiExport RemeshGmsh : public GmshWidget
     Q_OBJECT
 
 public:
-    RemeshGmsh(Mesh::Feature* mesh, QWidget* parent = 0, Qt::WindowFlags fl = 0);
+    RemeshGmsh(Mesh::Feature* mesh, QWidget* parent = 0, Qt::WindowFlags fl = Qt::WindowFlags());
     ~RemeshGmsh();
 
 protected:
diff --git a/src/Mod/Mesh/Gui/RemoveComponents.h b/src/Mod/Mesh/Gui/RemoveComponents.h
index 874e21e192..fa085551f3 100644
--- a/src/Mod/Mesh/Gui/RemoveComponents.h
+++ b/src/Mod/Mesh/Gui/RemoveComponents.h
@@ -42,7 +42,7 @@ class MeshGuiExport RemoveComponents : public QWidget
     Q_OBJECT
 
 public:
-    RemoveComponents(QWidget* parent = 0, Qt::WindowFlags fl = 0);
+    RemoveComponents(QWidget* parent = 0, Qt::WindowFlags fl = Qt::WindowFlags());
     ~RemoveComponents();
     void reject();
     void deleteSelection();
@@ -78,7 +78,7 @@ class MeshGuiExport RemoveComponentsDialog : public QDialog
     Q_OBJECT
 
 public:
-    RemoveComponentsDialog(QWidget* parent = 0, Qt::WindowFlags fl = 0);
+    RemoveComponentsDialog(QWidget* parent = 0, Qt::WindowFlags fl = Qt::WindowFlags());
     ~RemoveComponentsDialog();
     void reject();
 
diff --git a/src/Mod/Mesh/Gui/Segmentation.h b/src/Mod/Mesh/Gui/Segmentation.h
index 23e691c9e9..fd9755ffe8 100644
--- a/src/Mod/Mesh/Gui/Segmentation.h
+++ b/src/Mod/Mesh/Gui/Segmentation.h
@@ -37,7 +37,7 @@ class Ui_Segmentation;
 class MeshGuiExport Segmentation : public QWidget
 {
 public:
-    Segmentation(Mesh::Feature* mesh, QWidget* parent = 0, Qt::WindowFlags fl = 0);
+    Segmentation(Mesh::Feature* mesh, QWidget* parent = 0, Qt::WindowFlags fl = Qt::WindowFlags());
     ~Segmentation();
     void accept();
 
diff --git a/src/Mod/Mesh/Gui/SegmentationBestFit.h b/src/Mod/Mesh/Gui/SegmentationBestFit.h
index b1da47ce35..24c44d09a1 100644
--- a/src/Mod/Mesh/Gui/SegmentationBestFit.h
+++ b/src/Mod/Mesh/Gui/SegmentationBestFit.h
@@ -82,7 +82,7 @@ class MeshGuiExport SegmentationBestFit : public QWidget
     Q_OBJECT
 
 public:
-    SegmentationBestFit(Mesh::Feature* mesh, QWidget* parent = 0, Qt::WindowFlags fl = 0);
+    SegmentationBestFit(Mesh::Feature* mesh, QWidget* parent = 0, Qt::WindowFlags fl = Qt::WindowFlags());
     ~SegmentationBestFit();
     void accept();
 
diff --git a/src/Mod/MeshPart/Gui/CrossSections.h b/src/Mod/MeshPart/Gui/CrossSections.h
index 8cf044f424..a3abc64eb4 100644
--- a/src/Mod/MeshPart/Gui/CrossSections.h
+++ b/src/Mod/MeshPart/Gui/CrossSections.h
@@ -44,7 +44,7 @@ class CrossSections : public QDialog
     enum Plane { XY, XZ, YZ };
 
 public:
-    CrossSections(const Base::BoundBox3d& bb, QWidget* parent = 0, Qt::WindowFlags fl = 0);
+    CrossSections(const Base::BoundBox3d& bb, QWidget* parent = 0, Qt::WindowFlags fl = Qt::WindowFlags());
     ~CrossSections();
     void accept();
     void apply();
diff --git a/src/Mod/MeshPart/Gui/Tessellation.h b/src/Mod/MeshPart/Gui/Tessellation.h
index 1e42ed37ab..3d6033f16a 100644
--- a/src/Mod/MeshPart/Gui/Tessellation.h
+++ b/src/Mod/MeshPart/Gui/Tessellation.h
@@ -47,7 +47,7 @@ class Mesh2ShapeGmsh : public MeshGui::GmshWidget
     Q_OBJECT
 
 public:
-    Mesh2ShapeGmsh(QWidget* parent = 0, Qt::WindowFlags fl = 0);
+    Mesh2ShapeGmsh(QWidget* parent = 0, Qt::WindowFlags fl = Qt::WindowFlags());
     ~Mesh2ShapeGmsh();
 
     void process(App::Document* doc, const std::list<App::SubObjectT>&);
diff --git a/src/Mod/Part/Gui/CrossSections.h b/src/Mod/Part/Gui/CrossSections.h
index b22a9b8add..d73947bea8 100644
--- a/src/Mod/Part/Gui/CrossSections.h
+++ b/src/Mod/Part/Gui/CrossSections.h
@@ -44,7 +44,7 @@ class CrossSections : public QDialog
     enum Plane { XY, XZ, YZ };
 
 public:
-    CrossSections(const Base::BoundBox3d& bb, QWidget* parent = 0, Qt::WindowFlags fl = 0);
+    CrossSections(const Base::BoundBox3d& bb, QWidget* parent = 0, Qt::WindowFlags fl = Qt::WindowFlags());
     ~CrossSections();
     void accept();
     void apply();
diff --git a/src/Mod/Part/Gui/DlgExtrusion.h b/src/Mod/Part/Gui/DlgExtrusion.h
index b6822392a9..d1db3d860e 100644
--- a/src/Mod/Part/Gui/DlgExtrusion.h
+++ b/src/Mod/Part/Gui/DlgExtrusion.h
@@ -39,7 +39,7 @@ class DlgExtrusion : public QDialog, public Gui::SelectionObserver
     Q_OBJECT
 
 public:
-    DlgExtrusion(QWidget* parent = 0, Qt::WindowFlags fl = 0);
+    DlgExtrusion(QWidget* parent = 0, Qt::WindowFlags fl = Qt::WindowFlags());
     ~DlgExtrusion();
     void accept();
     void apply();
diff --git a/src/Mod/Part/Gui/DlgFilletEdges.h b/src/Mod/Part/Gui/DlgFilletEdges.h
index 65e25d3ff9..4f97cd96e2 100644
--- a/src/Mod/Part/Gui/DlgFilletEdges.h
+++ b/src/Mod/Part/Gui/DlgFilletEdges.h
@@ -81,7 +81,7 @@ class DlgFilletEdges : public QWidget, public Gui::SelectionObserver
 public:
     enum FilletType { FILLET, CHAMFER };
 
-    DlgFilletEdges(FilletType type, Part::FilletBase*, QWidget* parent = 0, Qt::WindowFlags fl = 0);
+    DlgFilletEdges(FilletType type, Part::FilletBase*, QWidget* parent = 0, Qt::WindowFlags fl = Qt::WindowFlags());
     ~DlgFilletEdges();
     bool accept();
 
@@ -121,7 +121,7 @@ class FilletEdgesDialog : public QDialog
     Q_OBJECT
 
 public:
-    FilletEdgesDialog(DlgFilletEdges::FilletType type, Part::FilletBase* fillet, QWidget* parent = 0, Qt::WindowFlags fl = 0);
+    FilletEdgesDialog(DlgFilletEdges::FilletType type, Part::FilletBase* fillet, QWidget* parent = 0, Qt::WindowFlags fl = Qt::WindowFlags());
     ~FilletEdgesDialog();
     void accept();
 
@@ -134,7 +134,7 @@ class DlgChamferEdges : public DlgFilletEdges
     Q_OBJECT
 
 public:
-    DlgChamferEdges(Part::FilletBase*, QWidget* parent = 0, Qt::WindowFlags fl = 0);
+    DlgChamferEdges(Part::FilletBase*, QWidget* parent = 0, Qt::WindowFlags fl = Qt::WindowFlags());
     ~DlgChamferEdges();
 
 protected:
diff --git a/src/Mod/Part/Gui/DlgPartBoxImp.h b/src/Mod/Part/Gui/DlgPartBoxImp.h
index 4428c077c4..15f3092cdc 100644
--- a/src/Mod/Part/Gui/DlgPartBoxImp.h
+++ b/src/Mod/Part/Gui/DlgPartBoxImp.h
@@ -34,7 +34,7 @@ class DlgPartBoxImp : public Gui::LocationDialogUiImp
     Q_OBJECT
 
 public:
-    DlgPartBoxImp(QWidget* parent = 0, Qt::WindowFlags fl = 0);
+    DlgPartBoxImp(QWidget* parent = 0, Qt::WindowFlags fl = Qt::WindowFlags());
     ~DlgPartBoxImp();
 };
 
diff --git a/src/Mod/Part/Gui/DlgPartCylinderImp.h b/src/Mod/Part/Gui/DlgPartCylinderImp.h
index 090b885e13..f4691cf37e 100644
--- a/src/Mod/Part/Gui/DlgPartCylinderImp.h
+++ b/src/Mod/Part/Gui/DlgPartCylinderImp.h
@@ -34,7 +34,7 @@ class DlgPartCylinderImp : public Gui::LocationDialogUiImp
     Q_OBJECT
 
 public:
-    DlgPartCylinderImp(QWidget* parent = 0, Qt::WindowFlags fl = 0);
+    DlgPartCylinderImp(QWidget* parent = 0, Qt::WindowFlags fl = Qt::WindowFlags());
     ~DlgPartCylinderImp();
 
     double getRadius() const;
diff --git a/src/Mod/Part/Gui/DlgPartImportIgesImp.h b/src/Mod/Part/Gui/DlgPartImportIgesImp.h
index cad4025dc8..0314c6225e 100644
--- a/src/Mod/Part/Gui/DlgPartImportIgesImp.h
+++ b/src/Mod/Part/Gui/DlgPartImportIgesImp.h
@@ -33,7 +33,7 @@ class DlgPartImportIgesImp : public QDialog
     Q_OBJECT
 
 public:
-  DlgPartImportIgesImp( QWidget* parent = 0, Qt::WindowFlags fl = 0 );
+  DlgPartImportIgesImp( QWidget* parent = 0, Qt::WindowFlags fl = Qt::WindowFlags() );
   ~DlgPartImportIgesImp();
 
 public Q_SLOTS:
diff --git a/src/Mod/Part/Gui/DlgPartImportStepImp.h b/src/Mod/Part/Gui/DlgPartImportStepImp.h
index 3e0984806f..39d917640a 100644
--- a/src/Mod/Part/Gui/DlgPartImportStepImp.h
+++ b/src/Mod/Part/Gui/DlgPartImportStepImp.h
@@ -34,7 +34,7 @@ class DlgPartImportStepImp : public QDialog
     Q_OBJECT
 
 public:
-  DlgPartImportStepImp( QWidget* parent = 0, Qt::WindowFlags fl = 0 );
+  DlgPartImportStepImp( QWidget* parent = 0, Qt::WindowFlags fl = Qt::WindowFlags() );
   ~DlgPartImportStepImp();
 
 public Q_SLOTS:
diff --git a/src/Mod/Part/Gui/DlgRevolution.h b/src/Mod/Part/Gui/DlgRevolution.h
index c05c98fa1e..2a8bf2bc8b 100644
--- a/src/Mod/Part/Gui/DlgRevolution.h
+++ b/src/Mod/Part/Gui/DlgRevolution.h
@@ -36,7 +36,7 @@ class DlgRevolution : public QDialog, public Gui::SelectionObserver
     Q_OBJECT
 
 public:
-    DlgRevolution(QWidget* parent = 0, Qt::WindowFlags fl = 0);
+    DlgRevolution(QWidget* parent = 0, Qt::WindowFlags fl = Qt::WindowFlags());
     ~DlgRevolution();
     void accept();
 
diff --git a/src/Mod/Points/Gui/DlgPointsReadImp.h b/src/Mod/Points/Gui/DlgPointsReadImp.h
index 7cd5943e77..693b6c2814 100644
--- a/src/Mod/Points/Gui/DlgPointsReadImp.h
+++ b/src/Mod/Points/Gui/DlgPointsReadImp.h
@@ -38,7 +38,7 @@ class DlgPointsReadImp : public QDialog
   Q_OBJECT
 
 public:
-  DlgPointsReadImp(const char *FileName, QWidget* parent = nullptr, Qt::WindowFlags fl = 0 );
+  DlgPointsReadImp(const char *FileName, QWidget* parent = nullptr, Qt::WindowFlags fl = Qt::WindowFlags() );
   ~DlgPointsReadImp();
 
 private:
diff --git a/src/Mod/ReverseEngineering/Gui/Segmentation.h b/src/Mod/ReverseEngineering/Gui/Segmentation.h
index ea9771d2ac..4e1ae9644c 100644
--- a/src/Mod/ReverseEngineering/Gui/Segmentation.h
+++ b/src/Mod/ReverseEngineering/Gui/Segmentation.h
@@ -41,7 +41,7 @@ class Segmentation : public QWidget
     Q_OBJECT
 
 public:
-    Segmentation(Mesh::Feature* mesh, QWidget* parent = 0, Qt::WindowFlags fl = 0);
+    Segmentation(Mesh::Feature* mesh, QWidget* parent = 0, Qt::WindowFlags fl = Qt::WindowFlags());
     ~Segmentation();
     void accept();
 
diff --git a/src/Mod/ReverseEngineering/Gui/SegmentationManual.h b/src/Mod/ReverseEngineering/Gui/SegmentationManual.h
index 2105459615..f7b7c0f0f4 100644
--- a/src/Mod/ReverseEngineering/Gui/SegmentationManual.h
+++ b/src/Mod/ReverseEngineering/Gui/SegmentationManual.h
@@ -43,7 +43,7 @@ class SegmentationManual : public QWidget
     Q_OBJECT
 
 public:
-    SegmentationManual(QWidget* parent = 0, Qt::WindowFlags fl = 0);
+    SegmentationManual(QWidget* parent = 0, Qt::WindowFlags fl = Qt::WindowFlags());
     ~SegmentationManual();
     void reject();
     void createSegment();
diff --git a/src/Mod/Start/Gui/Workbench.cpp b/src/Mod/Start/Gui/Workbench.cpp
index 41baf3deaf..de3140c1f2 100644
--- a/src/Mod/Start/Gui/Workbench.cpp
+++ b/src/Mod/Start/Gui/Workbench.cpp
@@ -85,35 +85,35 @@ void StartGui::Workbench::loadStartPage()
         std::string escapedstr = Base::Tools::escapedUnicodeFromUtf8(utf8Title);
         QByteArray cmd;
         QTextStream str(&cmd);
-        str << "import WebGui,sys,Start" << endl;
-        str << "from StartPage import StartPage" << endl;
+        str << "import WebGui,sys,Start" << Qt::endl;
+        str << "from StartPage import StartPage" << Qt::endl;
         str << endl;
-        str << "class WebPage(object):" << endl;
-        str << "    def __init__(self):" << endl;
-        str << "        self.browser=WebGui.openBrowserWindow(u'" << escapedstr.c_str() << "')" << endl;
+        str << "class WebPage(object):" << Qt::endl;
+        str << "    def __init__(self):" << Qt::endl;
+        str << "        self.browser=WebGui.openBrowserWindow(u'" << escapedstr.c_str() << "')" << Qt::endl;
 #if defined(FC_OS_WIN32)
-        str << "        self.browser.setHtml(StartPage.handle(), App.getResourceDir() + 'Mod/Start/StartPage/')" << endl;
+        str << "        self.browser.setHtml(StartPage.handle(), App.getResourceDir() + 'Mod/Start/StartPage/')" << Qt::endl;
 #else
-        str << "        self.browser.setHtml(StartPage.handle(), 'file://' + App.getResourceDir() + 'Mod/Start/StartPage/')" << endl;
+        str << "        self.browser.setHtml(StartPage.handle(), 'file://' + App.getResourceDir() + 'Mod/Start/StartPage/')" << Qt::endl;
 #endif
-        str << "    def onChange(self, par, reason):" << endl;
-        str << "        if reason == 'RecentFiles':" << endl;
+        str << "    def onChange(self, par, reason):" << Qt::endl;
+        str << "        if reason == 'RecentFiles':" << Qt::endl;
 #if defined(FC_OS_WIN32)
-        str << "            self.browser.setHtml(StartPage.handle(), App.getResourceDir() + 'Mod/Start/StartPage/')" << endl;
+        str << "            self.browser.setHtml(StartPage.handle(), App.getResourceDir() + 'Mod/Start/StartPage/')" << Qt::endl;
 #else
-        str << "            self.browser.setHtml(StartPage.handle(), 'file://' + App.getResourceDir() + 'Mod/Start/StartPage/')" << endl;
+        str << "            self.browser.setHtml(StartPage.handle(), 'file://' + App.getResourceDir() + 'Mod/Start/StartPage/')" << Qt::endl;
 #endif
+        str << Qt::endl;
+        str << "class WebView(object):" << Qt::endl;
+        str << "    def __init__(self):" << Qt::endl;
+        str << "        self.pargrp = FreeCAD.ParamGet('User parameter:BaseApp/Preferences/RecentFiles')" << Qt::endl;
+        str << "        self.webPage = WebPage()" << Qt::endl;
+        str << "        self.pargrp.Attach(self.webPage)" << Qt::endl;
+        str << "    def __del__(self):" << Qt::endl;
+        str << "        self.pargrp.Detach(self.webPage)" << Qt::endl;
         str << endl;
-        str << "class WebView(object):" << endl;
-        str << "    def __init__(self):" << endl;
-        str << "        self.pargrp = FreeCAD.ParamGet('User parameter:BaseApp/Preferences/RecentFiles')" << endl;
-        str << "        self.webPage = WebPage()" << endl;
-        str << "        self.pargrp.Attach(self.webPage)" << endl;
-        str << "    def __del__(self):" << endl;
-        str << "        self.pargrp.Detach(self.webPage)" << endl;
-        str << endl;
-        str << "webView=WebView()" << endl;
-        str << "StartPage.checkPostOpenStartPage()" << endl;
+        str << "webView=WebView()" << Qt::endl;
+        str << "StartPage.checkPostOpenStartPage()" << Qt::endl;
 
         Base::Interpreter().runString(cmd);
         // Gui::Command::runCommand(Gui::Command::Gui, cmd);
diff --git a/src/Mod/Test/Gui/UnitTestImp.h b/src/Mod/Test/Gui/UnitTestImp.h
index 22ff52d2a1..b8c56d2b4f 100644
--- a/src/Mod/Test/Gui/UnitTestImp.h
+++ b/src/Mod/Test/Gui/UnitTestImp.h
@@ -60,7 +60,7 @@ public:
     static bool hasInstance();
 
 protected:
-    UnitTestDialog(QWidget* parent = 0, Qt::WindowFlags f = 0);
+    UnitTestDialog(QWidget* parent = 0, Qt::WindowFlags f = Qt::WindowFlags());
     ~UnitTestDialog();
     void setProgressColor(const QColor& col);
 
diff --git a/src/Mod/Web/Gui/BrowserView.cpp b/src/Mod/Web/Gui/BrowserView.cpp
index be5f3131a1..33fe64f7cb 100644
--- a/src/Mod/Web/Gui/BrowserView.cpp
+++ b/src/Mod/Web/Gui/BrowserView.cpp
@@ -380,7 +380,7 @@ void WebView::triggerContextMenuAction(int id)
  *  name 'name'.
  */
 BrowserView::BrowserView(QWidget* parent)
-    : MDIView(0,parent,0),
+    : MDIView(0,parent,Qt::WindowFlags()),
       WindowParameter( "Browser" ),
       isLoading(false)
 {