diff --git a/src/Gui/Application.cpp b/src/Gui/Application.cpp
index 2bdf781c7a..eba0f11426 100644
--- a/src/Gui/Application.cpp
+++ b/src/Gui/Application.cpp
@@ -170,11 +170,7 @@ public:
 // Pimpl class
 struct ApplicationP
 {
-    explicit ApplicationP(bool GUIenabled) :
-    activeDocument(nullptr),
-    editDocument(nullptr),
-    isClosing(false),
-    startingUp(true)
+    explicit ApplicationP(bool GUIenabled)
     {
         // create the macro manager
         if (GUIenabled)
@@ -195,14 +191,14 @@ struct ApplicationP
     /// list of all handled documents
     std::map<const App::Document*, Gui::Document*> documents;
     /// Active document
-    Gui::Document*   activeDocument;
-    Gui::Document*  editDocument;
+    Gui::Document*   activeDocument{nullptr};
+    Gui::Document*  editDocument{nullptr};
     MacroManager*  macroMngr;
     PreferencePackManager* prefPackManager;
     /// List of all registered views
     std::list<Gui::BaseView*> passive;
-    bool isClosing;
-    bool startingUp;
+    bool isClosing{false};
+    bool startingUp{true};
     /// Handles all commands
     CommandManager commandManager;
     ViewProviderMap viewproviderMap;
diff --git a/src/Gui/AxisOrigin.cpp b/src/Gui/AxisOrigin.cpp
index 7851dc66d8..397f4b2b39 100644
--- a/src/Gui/AxisOrigin.cpp
+++ b/src/Gui/AxisOrigin.cpp
@@ -45,10 +45,7 @@ using namespace Gui;
 
 TYPESYSTEM_SOURCE(Gui::AxisOrigin,Base::BaseClass)
 
-AxisOrigin::AxisOrigin()
-    :size(6),pSize(4),dist(2),scale(1),lineSize(2),pointSize(4)
-{
-}
+AxisOrigin::AxisOrigin() = default;
 
 SoGroup *AxisOrigin::getNode() {
     if(node)
diff --git a/src/Gui/AxisOrigin.h b/src/Gui/AxisOrigin.h
index 33111e0208..c6aea015ea 100644
--- a/src/Gui/AxisOrigin.h
+++ b/src/Gui/AxisOrigin.h
@@ -93,12 +93,12 @@ public:
     bool getDetailPath(const char *subname, SoFullPath *pPath, SoDetail *&det) const;
 
 private:
-    float size;
-    float pSize;
-    float dist;
-    float scale;
-    float lineSize;
-    float pointSize;
+    float size = 6;
+    float pSize = 4;
+    float dist = 2;
+    float scale = 1;
+    float lineSize = 2;
+    float pointSize = 4;
     std::map<std::string, std::string> labels;
     CoinPtr<SoGroup> node;
     std::map<std::string, CoinPtr<SoNode> > nodeMap;
diff --git a/src/Gui/CallTips.h b/src/Gui/CallTips.h
index 259a2708b0..04473b074a 100644
--- a/src/Gui/CallTips.h
+++ b/src/Gui/CallTips.h
@@ -38,11 +38,10 @@ class CallTip
 {
 public:
     enum Type {Unknown, Module, Class, Method, Member, Property};
-    CallTip():type(Unknown) {}
     QString name;
     QString description;
     QString parameter;
-    Type type;
+    Type type{Unknown};
 };
 
 /**
diff --git a/src/Gui/Clipping.cpp b/src/Gui/Clipping.cpp
index 76d075a138..8238a04f67 100644
--- a/src/Gui/Clipping.cpp
+++ b/src/Gui/Clipping.cpp
@@ -48,11 +48,11 @@ public:
     SoClipPlane* clipY;
     SoClipPlane* clipZ;
     SoClipPlane* clipView;
-    bool flipX;
-    bool flipY;
-    bool flipZ;
+    bool flipX{false};
+    bool flipY{false};
+    bool flipZ{false};
     SoTimerSensor* sensor;
-    Private() : flipX(false), flipY(false), flipZ(false)
+    Private()
     {
         clipX = new SoClipPlane();
         clipX->on.setValue(false);
diff --git a/src/Gui/CommandDoc.cpp b/src/Gui/CommandDoc.cpp
index adb54d64ff..d0eb36a282 100644
--- a/src/Gui/CommandDoc.cpp
+++ b/src/Gui/CommandDoc.cpp
@@ -1681,10 +1681,6 @@ class StdCmdExpression : public Gui::Command
 {
 public:
     StdCmdExpression() : Command("Std_Expressions")
-                       , pcActionCopyAll(nullptr)
-                       , pcActionCopySel(nullptr)
-                       , pcActionCopyActive(nullptr)
-                       , pcActionPaste(nullptr)
     {
         sGroup        = "Edit";
         sMenuText     = QT_TR_NOOP("Expression actions");
@@ -1887,10 +1883,10 @@ protected:
         return true;
     }
 
-    QAction *pcActionCopyAll;
-    QAction *pcActionCopySel;
-    QAction *pcActionCopyActive;
-    QAction *pcActionPaste;
+    QAction *pcActionCopyAll{nullptr};
+    QAction *pcActionCopySel{nullptr};
+    QAction *pcActionCopyActive{nullptr};
+    QAction *pcActionPaste{nullptr};
 };
 
 namespace Gui {
diff --git a/src/Gui/CommandTest.cpp b/src/Gui/CommandTest.cpp
index 21014a228d..0a86fa47a7 100644
--- a/src/Gui/CommandTest.cpp
+++ b/src/Gui/CommandTest.cpp
@@ -722,10 +722,12 @@ class TestConsoleObserver : public Base::ILogger
 {
     QMutex mutex;
 public:
-    int matchMsg, matchWrn, matchErr, matchLog, matchCritical;
-    TestConsoleObserver() : matchMsg(0), matchWrn(0), matchErr(0), matchLog(0), matchCritical(0)
-    {
-    }
+    int matchMsg{0};
+    int matchWrn{0};
+    int matchErr{0};
+    int matchLog{0};
+    int matchCritical{0};
+    TestConsoleObserver() = default;
     void SendLog(const std::string& notifiername, const std::string& msg, Base::LogStyle level,
                  Base::IntendedRecipient recipient, Base::ContentType content) override{
 
diff --git a/src/Gui/CommandView.cpp b/src/Gui/CommandView.cpp
index c5af7a1f10..2ad6a44e85 100644
--- a/src/Gui/CommandView.cpp
+++ b/src/Gui/CommandView.cpp
@@ -305,24 +305,17 @@ private:
     void onRestoreViews();
 
 private:
-    const int maxViews;
-    int savedViews;
-    int offset;
-    QAction* saveView;
-    QAction* freezeView;
-    QAction* clearView;
-    QAction* separator;
+    const int maxViews{50};
+    int savedViews{0};
+    int offset{0};
+    QAction* saveView{nullptr};
+    QAction* freezeView{nullptr};
+    QAction* clearView{nullptr};
+    QAction* separator{nullptr};
 };
 
 StdCmdFreezeViews::StdCmdFreezeViews()
   : Command("Std_FreezeViews")
-  , maxViews(50)
-  , savedViews(0)
-  , offset(0)
-  , saveView(nullptr)
-  , freezeView(nullptr)
-  , clearView(nullptr)
-  , separator(nullptr)
 {
     sGroup        = "Standard-View";
     sMenuText     = QT_TR_NOOP("Freeze display");
diff --git a/src/Gui/DAGView/DAGFilter.cpp b/src/Gui/DAGView/DAGFilter.cpp
index 66bf9de621..57bc3915af 100644
--- a/src/Gui/DAGView/DAGFilter.cpp
+++ b/src/Gui/DAGView/DAGFilter.cpp
@@ -31,7 +31,7 @@
 using namespace Gui;
 using namespace DAG;
 
-FilterBase::FilterBase() : name(QString::fromLatin1("empty name")), enabled(true), type(Type::Exclusion)
+FilterBase::FilterBase() : name(QString::fromLatin1("empty name"))
 {
 
 }
diff --git a/src/Gui/DAGView/DAGFilter.h b/src/Gui/DAGView/DAGFilter.h
index 9b78af7308..788bc61899 100644
--- a/src/Gui/DAGView/DAGFilter.h
+++ b/src/Gui/DAGView/DAGFilter.h
@@ -45,8 +45,8 @@ namespace Gui
       //! @return is whether we have a match or not.
       virtual bool goFilter(const Vertex &vertexIn, const Graph &graphIn, const GraphLinkContainer &linkIn) const = 0;
       QString name;
-      bool enabled;
-      Type type;
+      bool enabled = true;
+      Type type = Type::Exclusion;
     };
 
     /*! Hide all children of app::origin that are not
diff --git a/src/Gui/DAGView/DAGModelGraph.cpp b/src/Gui/DAGView/DAGModelGraph.cpp
index 86c29bec51..f57171c3a9 100644
--- a/src/Gui/DAGView/DAGModelGraph.cpp
+++ b/src/Gui/DAGView/DAGModelGraph.cpp
@@ -34,13 +34,7 @@ VertexProperty::VertexProperty() :
   visibleIcon(new QGraphicsPixmapItem()),
   stateIcon(new QGraphicsPixmapItem()),
   icon(new QGraphicsPixmapItem()),
-  text(new QGraphicsTextItem()),
-  row(0),
-  column(0),
-  topoSortIndex(0),
-  lastVisibleState(VisibilityState::None),
-  lastFeatureState(FeatureState::None),
-  dagVisible(true)
+  text(new QGraphicsTextItem())
 {
   //set z values.
   this->rectangle->setZValue(-1000.0);
@@ -51,10 +45,7 @@ VertexProperty::VertexProperty() :
   this->text->setZValue(0.0);
 }
 
-EdgeProperty::EdgeProperty() : relation(BranchTag::None)
-{
-
-}
+EdgeProperty::EdgeProperty() = default;
 
 bool Gui::DAG::hasRecord(const App::DocumentObject* dObjectIn, const GraphLinkContainer &containerIn)
 {
diff --git a/src/Gui/DAGView/DAGModelGraph.h b/src/Gui/DAGView/DAGModelGraph.h
index e4b65c9363..27d0641e28 100644
--- a/src/Gui/DAGView/DAGModelGraph.h
+++ b/src/Gui/DAGView/DAGModelGraph.h
@@ -82,12 +82,12 @@ namespace Gui
       std::shared_ptr<QGraphicsPixmapItem> icon; //!< icon
       std::shared_ptr<QGraphicsTextItem> text; //!< text
       boost::signals2::connection connChangeIcon;
-      int row; //!< row for this entry.
-      ColumnMask column; //!< column number containing the point.
-      int topoSortIndex;
-      VisibilityState lastVisibleState; //!< visibility test.
-      FeatureState lastFeatureState; //!< feature state test.
-      bool dagVisible; //!< should entry be visible in the DAG view.
+      int row = 0; //!< row for this entry.
+      ColumnMask column = 0; //!< column number containing the point.
+      int topoSortIndex = 0;
+      VisibilityState lastVisibleState = VisibilityState::None; //!< visibility test.
+      FeatureState lastFeatureState = FeatureState::None; //!< feature state test.
+      bool dagVisible = true; //!< should entry be visible in the DAG view.
     };
     /*! @brief boost data for each vertex.
      *
@@ -114,7 +114,7 @@ namespace Gui
         Terminate       //!< terminate a branch.
       };
       EdgeProperty();
-      BranchTag relation;
+      BranchTag relation = BranchTag::None;
       std::shared_ptr <QGraphicsPathItem> connector; //!< line representing link between nodes.
     };
     /*! @brief needed to create an internal index for graph edges. needed for setS.*/
diff --git a/src/Gui/DlgCheckableMessageBox.cpp b/src/Gui/DlgCheckableMessageBox.cpp
index c4d206969b..7954190ffd 100644
--- a/src/Gui/DlgCheckableMessageBox.cpp
+++ b/src/Gui/DlgCheckableMessageBox.cpp
@@ -105,10 +105,10 @@ void DlgCheckableMessageBox::showMessage(const QString& header, const QString& m
 }
 
 struct DlgCheckableMessageBoxPrivate {
-    DlgCheckableMessageBoxPrivate() : clickedButton(nullptr) {}
+    DlgCheckableMessageBoxPrivate() = default;
 
     Ui::DlgCheckableMessageBox ui;
-    QAbstractButton *clickedButton;
+    QAbstractButton *clickedButton{nullptr};
 };
 
 DlgCheckableMessageBox::DlgCheckableMessageBox(QWidget *parent) :
diff --git a/src/Gui/DocumentModel.cpp b/src/Gui/DocumentModel.cpp
index afbe60169b..57308e4a8b 100644
--- a/src/Gui/DocumentModel.cpp
+++ b/src/Gui/DocumentModel.cpp
@@ -103,8 +103,8 @@ namespace Gui {
         { qDeleteAll(childItems); childItems.clear(); }
 
     protected:
-        DocumentModelIndex() : parentItem(nullptr) {}
-        DocumentModelIndex *parentItem;
+        DocumentModelIndex() = default;
+        DocumentModelIndex *parentItem{nullptr};
         QList<DocumentModelIndex*> childItems;
     };
 
diff --git a/src/Gui/DocumentObserver.cpp b/src/Gui/DocumentObserver.cpp
index 90d8168f2c..8d698db764 100644
--- a/src/Gui/DocumentObserver.cpp
+++ b/src/Gui/DocumentObserver.cpp
@@ -284,7 +284,7 @@ Gui::Document* DocumentWeakPtrT::operator->() const noexcept
 
 class ViewProviderWeakPtrT::Private {
 public:
-    Private(ViewProviderDocumentObject* obj) : object(obj), indocument(false) {
+    Private(ViewProviderDocumentObject* obj) : object(obj) {
         set(obj);
     }
     void deletedDocument(const Gui::Document& doc) {
@@ -338,7 +338,7 @@ public:
     }
 
     Gui::ViewProviderDocumentObject* object;
-    bool indocument;
+    bool indocument{false};
     using Connection = boost::signals2::scoped_connection;
     Connection connectApplicationDeletedDocument;
     Connection connectDocumentCreatedObject;
diff --git a/src/Gui/ExpressionBinding.cpp b/src/Gui/ExpressionBinding.cpp
index 72472fada9..2906ccec03 100644
--- a/src/Gui/ExpressionBinding.cpp
+++ b/src/Gui/ExpressionBinding.cpp
@@ -47,11 +47,7 @@ using namespace Gui;
 using namespace App;
 namespace sp = std::placeholders;
 
-ExpressionBinding::ExpressionBinding()
-    : m_autoApply(false)
-{
-}
-
+ExpressionBinding::ExpressionBinding() = default;
 
 ExpressionBinding::~ExpressionBinding() = default;
 
@@ -278,12 +274,7 @@ void ExpressionBinding::objectDeleted(const App::DocumentObject& obj)
 
 // ----------------------------------------------------------------------------
 
-ExpressionWidget::ExpressionWidget()
-    : iconLabel(nullptr)
-    , iconHeight(-1)
-{
-
-}
+ExpressionWidget::ExpressionWidget() = default;
 
 QPixmap ExpressionWidget::getIcon(const char* name, const QSize& size) const
 {
diff --git a/src/Gui/ExpressionBinding.h b/src/Gui/ExpressionBinding.h
index 65d1bc9eec..7183195f26 100644
--- a/src/Gui/ExpressionBinding.h
+++ b/src/Gui/ExpressionBinding.h
@@ -78,7 +78,7 @@ protected:
     void objectDeleted(const App::DocumentObject&);
     boost::signals2::scoped_connection expressionchanged;
     boost::signals2::scoped_connection objectdeleted;
-    bool m_autoApply;
+    bool m_autoApply{false};
 };
 
 class GuiExport ExpressionWidget : public ExpressionBinding
@@ -91,9 +91,9 @@ protected:
     void makeLabel(QLineEdit* parent);
 
 protected:
-    ExpressionLabel* iconLabel;
+    ExpressionLabel* iconLabel{nullptr};
     QPalette defaultPalette;
-    int iconHeight;
+    int iconHeight{-1};
 };
 
 }
diff --git a/src/Gui/GLBuffer.h b/src/Gui/GLBuffer.h
index c0d1c0812d..7955cfd884 100644
--- a/src/Gui/GLBuffer.h
+++ b/src/Gui/GLBuffer.h
@@ -24,6 +24,7 @@
 #ifndef GUI_GLBUFFER_H
 #define GUI_GLBUFFER_H
 
+#include <FCGlobal.h>
 #include <map>
 #include <Inventor/C/glue/gl.h>
 
diff --git a/src/Gui/GLPainter.cpp b/src/Gui/GLPainter.cpp
index 4844d64424..ed83191973 100644
--- a/src/Gui/GLPainter.cpp
+++ b/src/Gui/GLPainter.cpp
@@ -34,11 +34,6 @@ using namespace Gui;
 TYPESYSTEM_SOURCE_ABSTRACT(Gui::GLGraphicsItem, Base::BaseClass)
 
 GLPainter::GLPainter()
-  : viewer(nullptr)
-  , width(0)
-  , height(0)
-  , logicOp(false)
-  , lineStipple(false)
 {
     depthrange[0] = 0;
     depthrange[1] = 0;
diff --git a/src/Gui/GLPainter.h b/src/Gui/GLPainter.h
index 28a2294fb2..19e6bac343 100644
--- a/src/Gui/GLPainter.h
+++ b/src/Gui/GLPainter.h
@@ -75,12 +75,12 @@ public:
     //@}
 
 private:
-    QtGLWidget* viewer;
+    QtGLWidget* viewer{nullptr};
     GLfloat depthrange[2];
     GLdouble projectionmatrix[16];
-    GLint width, height;
-    bool logicOp;
-    bool lineStipple;
+    GLint width{0}, height{0};
+    bool logicOp{false};
+    bool lineStipple{false};
 };
 
 class GuiExport GLGraphicsItem : public Base::BaseClass
diff --git a/src/Gui/GestureNavigationStyle.cpp b/src/Gui/GestureNavigationStyle.cpp
index d8a362f276..b15296213a 100644
--- a/src/Gui/GestureNavigationStyle.cpp
+++ b/src/Gui/GestureNavigationStyle.cpp
@@ -93,7 +93,7 @@ namespace Gui {
 class NS::Event : public sc::event<NS::Event>
 {
 public:
-    Event():inventor_event(nullptr), modifiers{}, flags(new Flags){}
+    Event() : flags(new Flags){}
     virtual ~Event() = default;
 
     void log() const {
@@ -197,8 +197,8 @@ public:
     };
 
 public:
-    const SoEvent* inventor_event;
-    unsigned int modifiers;
+    const SoEvent* inventor_event{nullptr};
+    unsigned int modifiers{0};
     unsigned int mbstate() const {return modifiers & MASKBUTTONS;}
     unsigned int kbdstate() const {return modifiers & MASKMODIFIERS;}
 
diff --git a/src/Gui/GraphvizView.cpp b/src/Gui/GraphvizView.cpp
index 8bbfe8221a..2144365455 100644
--- a/src/Gui/GraphvizView.cpp
+++ b/src/Gui/GraphvizView.cpp
@@ -153,12 +153,11 @@ class GraphvizGraphicsView final : public QGraphicsView
     void mouseReleaseEvent(QMouseEvent *event) override;
 
   private:
-    bool   isPanning;
+    bool   isPanning{false};
     QPoint panStart;
 };
 
-GraphvizGraphicsView::GraphvizGraphicsView(QGraphicsScene* scene, QWidget* parent) : QGraphicsView(scene, parent),
-                                                                     isPanning(false)
+GraphvizGraphicsView::GraphvizGraphicsView(QGraphicsScene* scene, QWidget* parent) : QGraphicsView(scene, parent)
 {
 }
 
diff --git a/src/Gui/GuiApplication.cpp b/src/Gui/GuiApplication.cpp
index c297826795..a334766af4 100644
--- a/src/Gui/GuiApplication.cpp
+++ b/src/Gui/GuiApplication.cpp
@@ -167,8 +167,6 @@ public:
     explicit Private(GUISingleApplication *q_ptr)
       : q_ptr(q_ptr)
       , timer(new QTimer(q_ptr))
-      , server(nullptr)
-      , running(false)
     {
         timer->setSingleShot(true);
         std::string exeName = App::Application::getExecutableName();
@@ -218,10 +216,10 @@ public:
 
     GUISingleApplication *q_ptr;
     QTimer *timer;
-    QLocalServer *server;
+    QLocalServer *server{nullptr};
     QString serverName;
     QList<QByteArray> messages;
-    bool running;
+    bool running{false};
 };
 
 GUISingleApplication::GUISingleApplication(int & argc, char ** argv)
diff --git a/src/Gui/Macro.cpp b/src/Gui/Macro.cpp
index 46f37674e8..83e8f38de0 100644
--- a/src/Gui/Macro.cpp
+++ b/src/Gui/Macro.cpp
@@ -43,11 +43,7 @@
 
 using namespace Gui;
 
-MacroFile::MacroFile()
-  : openMacro(false)
-{
-
-}
+MacroFile::MacroFile() = default;
 
 void MacroFile::open(const char *sName)
 {
@@ -136,10 +132,7 @@ void MacroFile::cancel()
 
 // ----------------------------------------------------------------------------
 
-MacroOutputBuffer::MacroOutputBuffer()
-  : totalLines(0)
-{
-}
+MacroOutputBuffer::MacroOutputBuffer() = default;
 
 void MacroOutputBuffer::addPendingLine(int type, const char* line)
 {
@@ -170,12 +163,7 @@ void MacroOutputBuffer::incrementIfNoComment(int type)
 
 // ----------------------------------------------------------------------------
 
-MacroOutputOption::MacroOutputOption()
-  : recordGui(true)
-  , guiAsComment(true)
-  , scriptToPyConsole(true)
-{
-}
+MacroOutputOption::MacroOutputOption() = default;
 
 std::tuple<bool, bool> MacroOutputOption::values(int type) const
 {
@@ -213,9 +201,7 @@ bool MacroOutputOption::isAppCommand(int type)
 // ----------------------------------------------------------------------------
 
 MacroManager::MacroManager()
-  : localEnv(true),
-    pyConsole(nullptr),
-    pyDebugger(new PythonDebugger())
+  : pyDebugger(new PythonDebugger())
 {
     // Attach to the Parametergroup regarding macros
     this->params = App::GetApplication().GetParameterGroupByPath("User parameter:BaseApp/Preferences/Macro");
@@ -358,7 +344,7 @@ namespace Gui {
     class PythonRedirector
     {
     public:
-        PythonRedirector(const char* type, PyObject* obj) : std_out(type), out(obj), old(nullptr)
+        PythonRedirector(const char* type, PyObject* obj) : std_out(type), out(obj)
         {
             if (out) {
                 Base::PyGILStateLocker lock;
@@ -377,7 +363,7 @@ namespace Gui {
     private:
         const char* std_out;
         PyObject* out;
-        PyObject* old;
+        PyObject* old{nullptr};
     };
 }
 
diff --git a/src/Gui/Macro.h b/src/Gui/Macro.h
index 3b00702178..eeff49f568 100644
--- a/src/Gui/Macro.h
+++ b/src/Gui/Macro.h
@@ -56,7 +56,7 @@ public:
 private:
     QStringList macroInProgress;    /**< Container for the macro */
     QString macroName;              /**< name of the macro */
-    bool openMacro;
+    bool openMacro{false};
 };
 
 class MacroOutputBuffer
@@ -75,7 +75,7 @@ public:
     }
     void incrementIfNoComment(int type);
 
-    long totalLines;
+    long totalLines{0};
     std::vector<std::pair<int, std::string> > pendingLine;
 };
 
@@ -89,9 +89,9 @@ public:
     static bool isGuiCommand(int type);
     static bool isAppCommand(int type);
 
-    bool recordGui;
-    bool guiAsComment;
-    bool scriptToPyConsole;
+    bool recordGui{true};
+    bool guiAsComment{true};
+    bool scriptToPyConsole{true};
 };
 
 /** Macro recording and play back management
@@ -170,8 +170,8 @@ private:
     MacroFile macroFile;
     MacroOutputBuffer buffer;
     MacroOutputOption option;
-    bool localEnv;
-    mutable PythonConsole* pyConsole;       // link to the python console
+    bool localEnv{true};
+    mutable PythonConsole* pyConsole{nullptr};       // link to the python console
     PythonDebugger* pyDebugger;
     Base::Reference<ParameterGrp> params;  // link to the Macro parameter group
 
diff --git a/src/Gui/ManualAlignment.cpp b/src/Gui/ManualAlignment.cpp
index fbac6c0621..5f82f4a58b 100644
--- a/src/Gui/ManualAlignment.cpp
+++ b/src/Gui/ManualAlignment.cpp
@@ -471,13 +471,12 @@ class ManualAlignment::Private {
 public:
     SoSeparator * picksepLeft;
     SoSeparator * picksepRight;
-    SoNodeSensor* sensorCam1;
-    SoNodeSensor* sensorCam2;
+    SoNodeSensor* sensorCam1{nullptr};
+    SoNodeSensor* sensorCam2{nullptr};
     SbRotation rot_cam1, rot_cam2;
     SbVec3f pos_cam1, pos_cam2;
 
     Private()
-      : sensorCam1(nullptr), sensorCam2(nullptr)
     {
         // left view
         picksepLeft = new SoSeparator;
diff --git a/src/Gui/MergeDocuments.cpp b/src/Gui/MergeDocuments.cpp
index 09502d673c..aeafb24704 100644
--- a/src/Gui/MergeDocuments.cpp
+++ b/src/Gui/MergeDocuments.cpp
@@ -74,7 +74,7 @@ private:
 };
 }
 
-MergeDocuments::MergeDocuments(App::Document* doc) : stream(nullptr), appdoc(doc)
+MergeDocuments::MergeDocuments(App::Document* doc) : appdoc(doc)
 {
     //NOLINTBEGIN
     connectExport = doc->signalExportObjects.connect
diff --git a/src/Gui/MergeDocuments.h b/src/Gui/MergeDocuments.h
index 55eee8580b..d6945c0a79 100644
--- a/src/Gui/MergeDocuments.h
+++ b/src/Gui/MergeDocuments.h
@@ -27,6 +27,7 @@
 #include <Base/Persistence.h>
 #include <map>
 #include <vector>
+#include <boost/signals2.hpp>
 
 namespace zipios {
 class ZipInputStream;
@@ -53,7 +54,7 @@ public:
     void RestoreDocFile(Base::Reader & r) override;
 
 private:
-    zipios::ZipInputStream* stream;
+    zipios::ZipInputStream* stream{nullptr};
     App::Document* appdoc;
     Gui::Document* document;
     std::vector<App::DocumentObject*> objects;
diff --git a/src/Gui/MouseSelection.cpp b/src/Gui/MouseSelection.cpp
index 3c1c639cba..b05278cb09 100644
--- a/src/Gui/MouseSelection.cpp
+++ b/src/Gui/MouseSelection.cpp
@@ -38,7 +38,7 @@
 
 using namespace Gui;
 
-AbstractMouseSelection::AbstractMouseSelection() : _pcView3D(nullptr)
+AbstractMouseSelection::AbstractMouseSelection()
 {
     m_iXold = 0;
     m_iYold = 0;
diff --git a/src/Gui/MouseSelection.h b/src/Gui/MouseSelection.h
index 5191f22d2a..f798e25c41 100644
--- a/src/Gui/MouseSelection.h
+++ b/src/Gui/MouseSelection.h
@@ -95,7 +95,7 @@ protected:
     virtual void draw() {}
 
 protected:
-    Gui::View3DInventorViewer* _pcView3D;
+    Gui::View3DInventorViewer* _pcView3D{nullptr};
     QCursor m_cPrevCursor;
     int  m_iXold, m_iYold;
     int  m_iXnew, m_iYnew;
diff --git a/src/Gui/NavigationStyle.cpp b/src/Gui/NavigationStyle.cpp
index f35265f303..e3490ead43 100644
--- a/src/Gui/NavigationStyle.cpp
+++ b/src/Gui/NavigationStyle.cpp
@@ -90,7 +90,7 @@ public:
     };
 
     FCSphereSheetProjector(const SbSphere & sph, const SbBool orienttoeye = true)
-        : SbSphereSheetProjector(sph, orienttoeye), orbit(Trackball)
+        : SbSphereSheetProjector(sph, orienttoeye)
     {
     }
 
@@ -169,7 +169,7 @@ public:
 
 private:
     SbMatrix worldToScreen;
-    OrbitStyle orbit;
+    OrbitStyle orbit{Trackball};
 };
 
 NavigationStyleEvent::NavigationStyleEvent(const Base::Type& s)
diff --git a/src/Gui/NavigationStyle.h b/src/Gui/NavigationStyle.h
index 8d9b2dfb1a..cbc6204a9a 100644
--- a/src/Gui/NavigationStyle.h
+++ b/src/Gui/NavigationStyle.h
@@ -232,7 +232,7 @@ protected:
         SbTime * time;
     } log;
 
-    View3DInventorViewer* viewer;
+    View3DInventorViewer* viewer{nullptr};
     ViewerMode currentmode;
     SoMouseButtonEvent mouseDownConsumedEvent;
     SbVec2f lastmouseposition;
@@ -251,7 +251,7 @@ protected:
 
     /** @name Mouse model */
     //@{
-    AbstractMouseSelection* mouseSelection;
+    AbstractMouseSelection* mouseSelection{nullptr};
     std::vector<SbVec2s> pcPolygon;
     SelectionRole selectedRole;
     //@}
@@ -319,7 +319,7 @@ protected:
     SbBool processSoEvent(const SoEvent * const ev) override;
 
 private:
-    SbBool lockButton1;
+    SbBool lockButton1{false};
 };
 
 class GuiExport RevitNavigationStyle : public UserNavigationStyle {
@@ -336,7 +336,7 @@ protected:
     SbBool processSoEvent(const SoEvent * const ev) override;
 
 private:
-    SbBool lockButton1;
+    SbBool lockButton1{false};
 };
 
 class GuiExport BlenderNavigationStyle : public UserNavigationStyle {
@@ -353,7 +353,7 @@ protected:
     SbBool processSoEvent(const SoEvent * const ev) override;
 
 private:
-    SbBool lockButton1;
+    SbBool lockButton1{false};
 };
 
 class GuiExport MayaGestureNavigationStyle : public UserNavigationStyle {
diff --git a/src/Gui/PythonDebugger.cpp b/src/Gui/PythonDebugger.cpp
index 3b0aeab925..0d398c4d17 100644
--- a/src/Gui/PythonDebugger.cpp
+++ b/src/Gui/PythonDebugger.cpp
@@ -321,24 +321,20 @@ private:
 };
 
 struct PythonDebuggerP {
-    PyObject* out_o;
-    PyObject* err_o;
-    PyObject* exc_o;
-    PyObject* out_n;
-    PyObject* err_n;
-    PyObject* exc_n;
+    PyObject* out_o{nullptr};
+    PyObject* err_o{nullptr};
+    PyObject* exc_o{nullptr};
+    PyObject* out_n{nullptr};
+    PyObject* err_n{nullptr};
+    PyObject* exc_n{nullptr};
     PythonDebugExcept* pypde;
-    bool init, trystop, running;
+    bool init{false}, trystop{false}, running{false};
     QEventLoop loop;
-    PyObject* pydbg;
+    PyObject* pydbg{nullptr};
     std::vector<Breakpoint> bps;
 
-    explicit PythonDebuggerP(PythonDebugger* that) :
-        init(false), trystop(false), running(false)
+    explicit PythonDebuggerP(PythonDebugger* that)
     {
-        out_o = nullptr;
-        err_o = nullptr;
-        exc_o = nullptr;
         Base::PyGILStateLocker lock;
         out_n = new PythonDebugStdout();
         err_n = new PythonDebugStderr();
diff --git a/src/Gui/PythonEditor.cpp b/src/Gui/PythonEditor.cpp
index de015145aa..ffea4c72ba 100644
--- a/src/Gui/PythonEditor.cpp
+++ b/src/Gui/PythonEditor.cpp
@@ -43,15 +43,14 @@ using namespace Gui;
 namespace Gui {
 struct PythonEditorP
 {
-    int   debugLine;
+    int   debugLine{-1};
     QRect debugRect;
     QPixmap breakpoint;
     QPixmap debugMarker;
     QString filename;
     PythonDebugger* debugger;
     PythonEditorP()
-        : debugLine(-1),
-          breakpoint(BitmapFactory().iconFromTheme("breakpoint").pixmap(16,16)),
+        : breakpoint(BitmapFactory().iconFromTheme("breakpoint").pixmap(16,16)),
           debugMarker(BitmapFactory().iconFromTheme("debug-marker").pixmap(16,16))
     {
         debugger = Application::Instance->macroManager()->debugger();
diff --git a/src/Gui/Selection.cpp b/src/Gui/Selection.cpp
index 206588d213..d74f499f9c 100644
--- a/src/Gui/Selection.cpp
+++ b/src/Gui/Selection.cpp
@@ -1608,7 +1608,6 @@ void SelectionSingleton::slotDeletedObject(const App::DocumentObject& Obj)
  */
 SelectionSingleton::SelectionSingleton()
     :CurrentPreselection(SelectionChanges::ClrSelection)
-    ,_needPickedList(false)
 {
     hx = 0;
     hy = 0;
diff --git a/src/Gui/Selection.h b/src/Gui/Selection.h
index 56e3e9c503..32d4dac94b 100644
--- a/src/Gui/Selection.h
+++ b/src/Gui/Selection.h
@@ -671,7 +671,7 @@ protected:
     mutable std::list<_SelObj> _SelList;
 
     mutable std::list<_SelObj> _PickedList;
-    bool _needPickedList;
+    bool _needPickedList{false};
 
     using SelStackItem = std::set<App::SubObjectT>;
     std::deque<SelStackItem> _SelStackBack;
diff --git a/src/Gui/SoFCCSysDragger.cpp b/src/Gui/SoFCCSysDragger.cpp
index 05874a701c..038d09f22f 100644
--- a/src/Gui/SoFCCSysDragger.cpp
+++ b/src/Gui/SoFCCSysDragger.cpp
@@ -661,8 +661,7 @@ void SoFCCSysDragger::initClass()
 }
 
 SoFCCSysDragger::SoFCCSysDragger()
-    :axisScale(1.0f,1.0f,1.0f)
-    ,scaleInited(false)
+    : axisScale(1.0f,1.0f,1.0f)
 {
     SO_KIT_CONSTRUCTOR(SoFCCSysDragger);
 
diff --git a/src/Gui/SoFCCSysDragger.h b/src/Gui/SoFCCSysDragger.h
index 91aa418d68..66272cc916 100644
--- a/src/Gui/SoFCCSysDragger.h
+++ b/src/Gui/SoFCCSysDragger.h
@@ -264,7 +264,7 @@ private:
     // auto scale.
     SbVec3f axisScale;
 
-    bool scaleInited;
+    bool scaleInited{false};
 
     void updateAxisScale();
 
diff --git a/src/Gui/SoFCColorBar.cpp b/src/Gui/SoFCColorBar.cpp
index 638e6f9b61..64a12ae90a 100644
--- a/src/Gui/SoFCColorBar.cpp
+++ b/src/Gui/SoFCColorBar.cpp
@@ -46,7 +46,7 @@ SO_NODE_ABSTRACT_SOURCE(SoFCColorBarBase)
 /*!
   Constructor.
 */
-SoFCColorBarBase::SoFCColorBarBase() : _boxWidth(-1.0f), _windowSize(0,0)
+SoFCColorBarBase::SoFCColorBarBase() : _windowSize(0,0)
 {
     SO_NODE_CONSTRUCTOR(SoFCColorBarBase);
 }
diff --git a/src/Gui/SoFCColorBar.h b/src/Gui/SoFCColorBar.h
index 6f597c7ec1..5ad7acadfc 100644
--- a/src/Gui/SoFCColorBar.h
+++ b/src/Gui/SoFCColorBar.h
@@ -138,7 +138,7 @@ protected:
   ~SoFCColorBarBase () override;
 
 private:
-  float _boxWidth;
+  float _boxWidth{-1.0F};
   SbVec2s _windowSize;
 };
 
diff --git a/src/Gui/SoFCColorGradient.cpp b/src/Gui/SoFCColorGradient.cpp
index e32553acbe..ae36f585b4 100644
--- a/src/Gui/SoFCColorGradient.cpp
+++ b/src/Gui/SoFCColorGradient.cpp
@@ -50,7 +50,7 @@ SO_NODE_SOURCE(SoFCColorGradient)
 /*!
   Constructor.
 */
-SoFCColorGradient::SoFCColorGradient() : _bbox(5.0f, -4.0f, 5.5f, 4.0f), _precision(3)
+SoFCColorGradient::SoFCColorGradient() : _bbox(5.0f, -4.0f, 5.5f, 4.0f)
 {
     SO_NODE_CONSTRUCTOR(SoFCColorGradient);
     coords = new SoCoordinate3;
diff --git a/src/Gui/SoFCColorGradient.h b/src/Gui/SoFCColorGradient.h
index 7fd6b42815..478668a326 100644
--- a/src/Gui/SoFCColorGradient.h
+++ b/src/Gui/SoFCColorGradient.h
@@ -103,7 +103,7 @@ private:
   SoCoordinate3* coords;
   SoSeparator* labels;
   SbBox2f _bbox;
-  int _precision;
+  int _precision{3};
   App::ColorGradient _cColGrad;
 };
 
diff --git a/src/Gui/SoFCInteractiveElement.cpp b/src/Gui/SoFCInteractiveElement.cpp
index fc9deb97af..497ddd62dc 100644
--- a/src/Gui/SoFCInteractiveElement.cpp
+++ b/src/Gui/SoFCInteractiveElement.cpp
@@ -180,7 +180,7 @@ SO_NODE_SOURCE(SoGLWidgetNode)
 /*!
   Constructor.
 */
-SoGLWidgetNode::SoGLWidgetNode() : window(nullptr)
+SoGLWidgetNode::SoGLWidgetNode()
 {
     SO_NODE_CONSTRUCTOR(SoGLWidgetNode);
 }
diff --git a/src/Gui/SoFCInteractiveElement.h b/src/Gui/SoFCInteractiveElement.h
index d8ad66def7..41eb54ca37 100644
--- a/src/Gui/SoFCInteractiveElement.h
+++ b/src/Gui/SoFCInteractiveElement.h
@@ -117,7 +117,7 @@ public:
     static void initClass();
     SoGLWidgetNode();
 
-    QtGLWidget * window;
+    QtGLWidget * window{nullptr};
 
     void doAction(SoAction * action) override;
     void GLRender(SoGLRenderAction * action) override;
diff --git a/src/Gui/SoFCSelectionAction.cpp b/src/Gui/SoFCSelectionAction.cpp
index 141a2cbfc0..14777bd78b 100644
--- a/src/Gui/SoFCSelectionAction.cpp
+++ b/src/Gui/SoFCSelectionAction.cpp
@@ -692,7 +692,7 @@ void SoFCDocumentObjectAction::finish()
   atexit_cleanup();
 }
 
-SoFCDocumentObjectAction::SoFCDocumentObjectAction () : _handled(false)
+SoFCDocumentObjectAction::SoFCDocumentObjectAction()
 {
   SO_ACTION_CONSTRUCTOR(SoFCDocumentObjectAction);
 }
@@ -760,7 +760,7 @@ void SoGLSelectAction::initClass()
 
 SoGLSelectAction::SoGLSelectAction (const SbViewportRegion& region,
                                     const SbViewportRegion& select)
-  : vpregion(region), vpselect(select), _handled(false)
+  : vpregion(region), vpselect(select)
 {
   SO_ACTION_CONSTRUCTOR(SoGLSelectAction);
 }
@@ -833,7 +833,7 @@ void SoVisibleFaceAction::initClass()
   SO_ACTION_ADD_METHOD(SoFCSelection,callDoAction);
 }
 
-SoVisibleFaceAction::SoVisibleFaceAction () : _handled(false)
+SoVisibleFaceAction::SoVisibleFaceAction ()
 {
   SO_ACTION_CONSTRUCTOR(SoVisibleFaceAction);
 }
@@ -930,33 +930,21 @@ class SoBoxSelectionRenderActionP {
 public:
     SoBoxSelectionRenderActionP(SoBoxSelectionRenderAction * master)
       : master(master)
-      , searchaction(nullptr)
-      , selectsearch(nullptr)
-      , camerasearch(nullptr)
-      , bboxaction(nullptr)
-      , basecolor(nullptr)
-      , postprocpath(nullptr)
-      , highlightPath(nullptr)
-      , localRoot(nullptr)
-      , xform(nullptr)
-      , cube(nullptr)
-      , drawstyle(nullptr)
     {
-
     }
 
     SoBoxSelectionRenderAction * master;
-    SoSearchAction * searchaction;
-    SoSearchAction * selectsearch;
-    SoSearchAction * camerasearch;
-    SoGetBoundingBoxAction * bboxaction;
-    SoBaseColor * basecolor;
-    SoTempPath * postprocpath;
-    SoPath * highlightPath;
-    SoSeparator * localRoot;
-    SoMatrixTransform * xform;
-    SoCube * cube;
-    SoDrawStyle * drawstyle;
+    SoSearchAction * searchaction{nullptr};
+    SoSearchAction * selectsearch{nullptr};
+    SoSearchAction * camerasearch{nullptr};
+    SoGetBoundingBoxAction * bboxaction{nullptr};
+    SoBaseColor * basecolor{nullptr};
+    SoTempPath * postprocpath{nullptr};
+    SoPath * highlightPath{nullptr};
+    SoSeparator * localRoot{nullptr};
+    SoMatrixTransform * xform{nullptr};
+    SoCube * cube{nullptr};
+    SoDrawStyle * drawstyle{nullptr};
     SoColorPacker colorpacker;
 
     void initBoxGraph();
diff --git a/src/Gui/SoFCSelectionAction.h b/src/Gui/SoFCSelectionAction.h
index 4661d3fd54..7576ca911a 100644
--- a/src/Gui/SoFCSelectionAction.h
+++ b/src/Gui/SoFCSelectionAction.h
@@ -243,7 +243,7 @@ public:
     SbString componentName;
 
 private:
-    SbBool _handled;
+    SbBool _handled{false};
 };
 
 /**
@@ -276,7 +276,7 @@ public:
 private:
     const SbViewportRegion& vpregion;
     const SbViewportRegion& vpselect;
-    SbBool _handled;
+    SbBool _handled{false};
 };
 
 /**
@@ -302,7 +302,7 @@ private:
     static void callDoAction(SoAction *action,SoNode *node);
 
 private:
-    SbBool _handled;
+    SbBool _handled{false};
 };
 
 class SoBoxSelectionRenderActionP;
diff --git a/src/Gui/SoFCSelectionContext.cpp b/src/Gui/SoFCSelectionContext.cpp
index 2e5e27c6f8..ee5a73849e 100644
--- a/src/Gui/SoFCSelectionContext.cpp
+++ b/src/Gui/SoFCSelectionContext.cpp
@@ -237,12 +237,9 @@ int SoFCSelectionContextEx::merge(int status, SoFCSelectionContextBasePtr &outpu
 ///////////////////////////////////////////////////////////////////////
 
 SoFCSelectionCounter::SoFCSelectionCounter()
-    :counter(std::make_shared<int>(0))
-    ,hasSelection(false)
-    ,hasPreselection(false)
+  : counter(std::make_shared<int>(0))
 {}
 
-
 SoFCSelectionCounter::~SoFCSelectionCounter() = default;
 
 
diff --git a/src/Gui/SoFCSelectionContext.h b/src/Gui/SoFCSelectionContext.h
index 5c22d8bc3b..390e57a018 100644
--- a/src/Gui/SoFCSelectionContext.h
+++ b/src/Gui/SoFCSelectionContext.h
@@ -32,6 +32,7 @@
 
 #include <App/Material.h>
 
+class SoState;
 
 namespace Gui {
 
@@ -131,8 +132,8 @@ public:
     void checkAction(SoSelectionElementAction *selaction, SoFCSelectionContextPtr ctx);
 protected:
     std::shared_ptr<int> counter;
-    bool hasSelection;
-    bool hasPreselection;
+    bool hasSelection{false};
+    bool hasPreselection{false};
     static int cachingMode;
 };
 
diff --git a/src/Gui/SoFCUnifiedSelection.cpp b/src/Gui/SoFCUnifiedSelection.cpp
index fb7261e462..b33811c7e6 100644
--- a/src/Gui/SoFCUnifiedSelection.cpp
+++ b/src/Gui/SoFCUnifiedSelection.cpp
@@ -102,7 +102,7 @@ SO_NODE_SOURCE(SoFCUnifiedSelection)
 /*!
   Constructor.
 */
-SoFCUnifiedSelection::SoFCUnifiedSelection() : pcDocument(nullptr)
+SoFCUnifiedSelection::SoFCUnifiedSelection()
 {
     SO_NODE_CONSTRUCTOR(SoFCUnifiedSelection);
 
@@ -794,7 +794,7 @@ void SoHighlightElementAction::initClass()
     SO_ACTION_ADD_METHOD(SoPointSet,callDoAction);
 }
 
-SoHighlightElementAction::SoHighlightElementAction () : _highlight(false), _det(nullptr)
+SoHighlightElementAction::SoHighlightElementAction ()
 {
     SO_ACTION_CONSTRUCTOR(SoHighlightElementAction);
 }
@@ -863,7 +863,7 @@ void SoSelectionElementAction::initClass()
 }
 
 SoSelectionElementAction::SoSelectionElementAction (Type t, bool secondary)
-    : _type(t), _det(nullptr), _secondary(secondary)
+    : _type(t), _secondary(secondary)
 {
     SO_ACTION_CONSTRUCTOR(SoSelectionElementAction);
 }
@@ -933,7 +933,7 @@ void SoVRMLAction::initClass()
     SO_ACTION_ADD_METHOD(SoPointSet,callDoAction);
 }
 
-SoVRMLAction::SoVRMLAction() : overrideMode(true)
+SoVRMLAction::SoVRMLAction()
 {
     SO_ACTION_CONSTRUCTOR(SoVRMLAction);
 }
diff --git a/src/Gui/SoFCUnifiedSelection.h b/src/Gui/SoFCUnifiedSelection.h
index 06c4daadc0..8fe068d2bc 100644
--- a/src/Gui/SoFCUnifiedSelection.h
+++ b/src/Gui/SoFCUnifiedSelection.h
@@ -104,11 +104,9 @@ private:
     static int getPriority(const SoPickedPoint* p);
 
     struct PickedInfo {
-        const SoPickedPoint *pp;
-        ViewProviderDocumentObject *vpd;
+        const SoPickedPoint *pp{nullptr};
+        ViewProviderDocumentObject *vpd{nullptr};
         std::string element;
-        PickedInfo():pp(nullptr),vpd(nullptr)
-        {}
     };
 
     bool setHighlight(const PickedInfo &);
@@ -118,7 +116,7 @@ private:
 
     std::vector<PickedInfo> getPickedList(SoHandleEventAction* action, bool singlePick) const;
 
-    Gui::Document       *pcDocument;
+    Gui::Document       *pcDocument{nullptr};
 
     static SoFullPath * currenthighlight;
     SoFullPath * detailPath;
@@ -403,9 +401,9 @@ private:
     static void callDoAction(SoAction *action,SoNode *node);
 
 private:
-    SbBool _highlight;
+    SbBool _highlight{false};
     SbColor _color;
-    const SoDetail* _det;
+    const SoDetail* _det{nullptr};
 };
 
 /**
@@ -457,7 +455,7 @@ private:
 private:
     Type _type;
     SbColor _color;
-    const SoDetail* _det;
+    const SoDetail* _det{nullptr};
     std::map<std::string,App::Color> _colors;
     bool _secondary;
 };
@@ -478,7 +476,7 @@ public:
     static void initClass();
 
 private:
-    SbBool overrideMode;
+    SbBool overrideMode{true};
     std::list<int> bindList;
     static void callDoAction(SoAction *action,SoNode *node);
 
diff --git a/src/Gui/SoFCVectorizeSVGAction.cpp b/src/Gui/SoFCVectorizeSVGAction.cpp
index 9054177e73..449d858c32 100644
--- a/src/Gui/SoFCVectorizeSVGAction.cpp
+++ b/src/Gui/SoFCVectorizeSVGAction.cpp
@@ -376,10 +376,7 @@ void SoFCVectorizeSVGAction::initClass()
     SO_ACTION_INIT_CLASS(SoFCVectorizeSVGAction, SoVectorizeAction);
 }
 
-SoFCVectorizeSVGAction::SoFCVectorizeSVGAction() :
-    m_backgroundState(true),
-    m_lineWidth(1.0),
-    m_usemm(false)
+SoFCVectorizeSVGAction::SoFCVectorizeSVGAction()
 {
     SO_ACTION_CONSTRUCTOR(SoFCVectorizeSVGAction);
     this->setOutput(new SoSVGVectorOutput);
diff --git a/src/Gui/SoFCVectorizeSVGAction.h b/src/Gui/SoFCVectorizeSVGAction.h
index 6325b4e1c0..fdc3e6873d 100644
--- a/src/Gui/SoFCVectorizeSVGAction.h
+++ b/src/Gui/SoFCVectorizeSVGAction.h
@@ -78,9 +78,9 @@ protected:
 private:
     SoFCVectorizeSVGActionP* p;
     friend class SoFCVectorizeSVGActionP;
-    bool m_backgroundState;
-    double m_lineWidth;
-    bool m_usemm;
+    bool m_backgroundState{true};
+    double m_lineWidth{1.0};
+    bool m_usemm{false};
 };
 
 } // namespace Gui
diff --git a/src/Gui/SoTouchEvents.h b/src/Gui/SoTouchEvents.h
index c7d16c5e94..3df1dc96ea 100644
--- a/src/Gui/SoTouchEvents.h
+++ b/src/Gui/SoTouchEvents.h
@@ -39,7 +39,7 @@ public:
     static void initClass(){
         SO_EVENT_INIT_CLASS(SoGestureEvent, SoEvent);
     }
-    SoGestureEvent() : state(SbGSNoGesture) {}
+    SoGestureEvent() = default;
     ~SoGestureEvent() override = default;
     SbBool isSoGestureEvent(const SoEvent* ev) const;
 
@@ -50,7 +50,7 @@ public:
         SbGSEnd = Qt::GestureFinished,
         SbGsCanceled = Qt::GestureCanceled
     };
-    SbGestureState state;
+    SbGestureState state{SbGSNoGesture};
 };
 
 class SoGesturePanEvent : public SoGestureEvent {
diff --git a/src/Gui/SpaceballEvent.cpp b/src/Gui/SpaceballEvent.cpp
index 7c4b004376..f383121761 100644
--- a/src/Gui/SpaceballEvent.cpp
+++ b/src/Gui/SpaceballEvent.cpp
@@ -31,16 +31,15 @@ int MotionEvent::MotionEventType = -1;
 int ButtonEvent::ButtonEventType = -1;
 
 #if QT_VERSION < QT_VERSION_CHECK(6,0,0)
-EventBase::EventBase(QEvent::Type event) : QInputEvent(static_cast<QEvent::Type>(event)), handled(false)
+EventBase::EventBase(QEvent::Type event) : QInputEvent(static_cast<QEvent::Type>(event))
 #else
-EventBase::EventBase(QEvent::Type event) : QInputEvent(static_cast<QEvent::Type>(event), QPointingDevice::primaryPointingDevice()), handled(false)
+EventBase::EventBase(QEvent::Type event) : QInputEvent(static_cast<QEvent::Type>(event), QPointingDevice::primaryPointingDevice())
 #endif
 {
 
 }
 
-MotionEvent::MotionEvent() : EventBase(static_cast<QEvent::Type>(MotionEventType)),
-    xTrans(0), yTrans(0), zTrans(0), xRot(0), yRot(0), zRot(0)
+MotionEvent::MotionEvent() : EventBase(static_cast<QEvent::Type>(MotionEventType))
 {
 }
 
diff --git a/src/Gui/SpaceballEvent.h b/src/Gui/SpaceballEvent.h
index ea56fc6d23..32f16a1bc3 100644
--- a/src/Gui/SpaceballEvent.h
+++ b/src/Gui/SpaceballEvent.h
@@ -37,7 +37,7 @@ namespace Spaceball
 
     protected:
         explicit EventBase(QEvent::Type event);
-        bool handled;
+        bool handled{false};
     };
 
     class MotionEvent : public EventBase
@@ -61,12 +61,12 @@ namespace Spaceball
         static int MotionEventType;
 
     private:
-        int xTrans;
-        int yTrans;
-        int zTrans;
-        int xRot;
-        int yRot;
-        int zRot;
+        int xTrans{0};
+        int yTrans{0};
+        int zTrans{0};
+        int xRot{0};
+        int yRot{0};
+        int zRot{0};
     };
 
     class ButtonEvent : public EventBase
diff --git a/src/Gui/SpinBox.cpp b/src/Gui/SpinBox.cpp
index abd3c7076a..85113b3df2 100644
--- a/src/Gui/SpinBox.cpp
+++ b/src/Gui/SpinBox.cpp
@@ -278,11 +278,9 @@ namespace Gui {
 class UIntSpinBoxPrivate
 {
 public:
-    UnsignedValidator * mValidator;
+    UnsignedValidator * mValidator{nullptr};
 
-    UIntSpinBoxPrivate() : mValidator(nullptr)
-    {
-    }
+    UIntSpinBoxPrivate() = default;
     uint mapToUInt( int v ) const
     {
         uint ui;
diff --git a/src/Gui/Thumbnail.cpp b/src/Gui/Thumbnail.cpp
index 016c6e57e3..ac0962e155 100644
--- a/src/Gui/Thumbnail.cpp
+++ b/src/Gui/Thumbnail.cpp
@@ -42,7 +42,7 @@
 
 using namespace Gui;
 
-Thumbnail::Thumbnail(int s) : viewer(nullptr), size(s)
+Thumbnail::Thumbnail(int s) : size(s)
 {
 }
 
diff --git a/src/Gui/Thumbnail.h b/src/Gui/Thumbnail.h
index 2563ef30df..54176b13a1 100644
--- a/src/Gui/Thumbnail.h
+++ b/src/Gui/Thumbnail.h
@@ -57,7 +57,7 @@ public:
 
 private:
     QUrl uri;
-    View3DInventorViewer* viewer;
+    View3DInventorViewer* viewer{nullptr};
     int size;
 };
 
diff --git a/src/Gui/ToolBoxManager.cpp b/src/Gui/ToolBoxManager.cpp
index 1c7087eb5a..f1912c9493 100644
--- a/src/Gui/ToolBoxManager.cpp
+++ b/src/Gui/ToolBoxManager.cpp
@@ -53,9 +53,7 @@ void ToolBoxManager::destruct()
     _instance = nullptr;
 }
 
-ToolBoxManager::ToolBoxManager() : _toolBox(nullptr)
-{
-}
+ToolBoxManager::ToolBoxManager() = default;
 
 ToolBoxManager::~ToolBoxManager() = default;
 
diff --git a/src/Gui/ToolBoxManager.h b/src/Gui/ToolBoxManager.h
index 4bb8025bd8..2c527f2ce4 100644
--- a/src/Gui/ToolBoxManager.h
+++ b/src/Gui/ToolBoxManager.h
@@ -24,6 +24,8 @@
 #ifndef GUI_TOOLBOXMANAGER_H
 #define GUI_TOOLBOXMANAGER_H
 
+#include <FCGlobal.h>
+
 namespace Gui {
 
 class ToolBarItem;
@@ -55,7 +57,7 @@ protected:
     ~ToolBoxManager();
 
 private:
-    DockWnd::ToolBox* _toolBox;
+    DockWnd::ToolBox* _toolBox{nullptr};
     static ToolBoxManager* _instance;
 };
 
diff --git a/src/Gui/Tree.cpp b/src/Gui/Tree.cpp
index 0a63be3bf3..2dfab108ad 100644
--- a/src/Gui/Tree.cpp
+++ b/src/Gui/Tree.cpp
@@ -199,7 +199,7 @@ public:
     DocumentItem* docItem;
     DocumentObjectItems items;
     ViewProviderDocumentObject* viewObject;
-    DocumentObjectItem* rootItem;
+    DocumentObjectItem* rootItem{nullptr};
     std::vector<App::DocumentObject*> children;
     std::set<App::DocumentObject*> childSet;
     bool removeChildrenFromRoot;
@@ -214,7 +214,8 @@ public:
     Connection connectStat;
 
     DocumentObjectData(DocumentItem* docItem, ViewProviderDocumentObject* vpd)
-        : docItem(docItem), viewObject(vpd), rootItem(nullptr)
+        : docItem(docItem)
+        , viewObject(vpd)
     {
         //NOLINTBEGIN
         // Setup connections
@@ -2433,13 +2434,13 @@ void TreeWidget::slotActiveDocument(const Gui::Document& Doc)
 struct UpdateDisabler {
     QWidget& widget;
     int& blocked;
-    bool visible;
-    bool focus;
+    bool visible{false};
+    bool focus{false};
 
     // Note! DO NOT block signal here, or else
     // QTreeWidgetItem::setChildIndicatorPolicy() does not work
     UpdateDisabler(QWidget& w, int& blocked)
-        : widget(w), blocked(blocked), visible(false), focus(false)
+        : widget(w), blocked(blocked)
     {
         if (++blocked > 1)
             return;
diff --git a/src/Gui/View.cpp b/src/Gui/View.cpp
index 486f7e3f4f..bbd0010ac5 100644
--- a/src/Gui/View.cpp
+++ b/src/Gui/View.cpp
@@ -37,7 +37,7 @@ TYPESYSTEM_SOURCE_ABSTRACT(Gui::BaseView,Base::BaseClass)
 
 
 BaseView::BaseView( Gui::Document* pcDocument)
-  :_pcDocument(pcDocument), bIsDetached(false)
+  :_pcDocument(pcDocument)
 {
     if (pcDocument){
         pcDocument->attachView(this);
diff --git a/src/Gui/View.h b/src/Gui/View.h
index fd588e6145..c09bcdfd0d 100644
--- a/src/Gui/View.h
+++ b/src/Gui/View.h
@@ -105,8 +105,8 @@ public:
 
 protected:
     Gui::Document*  _pcDocument;
-    bool bIsDetached;
-    bool bIsPassive;
+    bool bIsDetached{false};
+    bool bIsPassive{false};
 };
 
 } // namespace Gui
diff --git a/src/Gui/ViewProvider.cpp b/src/Gui/ViewProvider.cpp
index 5d9dacb527..63f813d75a 100644
--- a/src/Gui/ViewProvider.cpp
+++ b/src/Gui/ViewProvider.cpp
@@ -88,12 +88,7 @@ void coinRemoveAllChildren(SoGroup *group) {
 PROPERTY_SOURCE_ABSTRACT(Gui::ViewProvider, App::TransactionalObject)
 
 ViewProvider::ViewProvider()
-    : pcAnnotation(nullptr)
-    , pyViewObject(nullptr)
-    , overrideMode("As Is")
-    , _iActualMode(-1)
-    , _iEditMode(-1)
-    , viewOverrideMode(-1)
+    : overrideMode("As Is")
 {
     setStatus(UpdateData, true);
 
diff --git a/src/Gui/ViewProvider.h b/src/Gui/ViewProvider.h
index 6e882e7e19..a319ec0c8d 100644
--- a/src/Gui/ViewProvider.h
+++ b/src/Gui/ViewProvider.h
@@ -564,15 +564,15 @@ protected:
     /// this is the mode switch, all the different viewing modes are collected here
     SoSwitch    *pcModeSwitch;
     /// The root separator for annotations
-    SoSeparator *pcAnnotation;
-    ViewProviderPy* pyViewObject;
+    SoSeparator *pcAnnotation{nullptr};
+    ViewProviderPy* pyViewObject{nullptr};
     std::string overrideMode;
     std::bitset<32> StatusBits;
 
 private:
-    int _iActualMode;
-    int _iEditMode;
-    int viewOverrideMode;
+    int _iActualMode{-1};
+    int _iEditMode{-1};
+    int viewOverrideMode{-1};
     std::string _sCurrentMode;
     std::map<std::string, int> _sDisplayMaskModes;
 };
diff --git a/src/Gui/ViewProviderDocumentObject.cpp b/src/Gui/ViewProviderDocumentObject.cpp
index 8286f6a214..31dd847fba 100644
--- a/src/Gui/ViewProviderDocumentObject.cpp
+++ b/src/Gui/ViewProviderDocumentObject.cpp
@@ -58,8 +58,6 @@ using namespace Gui;
 PROPERTY_SOURCE(Gui::ViewProviderDocumentObject, Gui::ViewProvider)
 
 ViewProviderDocumentObject::ViewProviderDocumentObject()
-  : pcObject(nullptr)
-  , pcDocument(nullptr)
 {
     static const char *dogroup = "Display Options";
     static const char *sgroup = "Selection";
diff --git a/src/Gui/ViewProviderDocumentObject.h b/src/Gui/ViewProviderDocumentObject.h
index f01c808069..14b8cd38c6 100644
--- a/src/Gui/ViewProviderDocumentObject.h
+++ b/src/Gui/ViewProviderDocumentObject.h
@@ -210,8 +210,8 @@ protected:
     void addDefaultAction(QMenu*, const QString&);
 
 protected:
-    App::DocumentObject *pcObject;
-    Gui::Document* pcDocument;
+    App::DocumentObject *pcObject{nullptr};
+    Gui::Document* pcDocument{nullptr};
 
 private:
     bool _Showable = true;
diff --git a/src/Gui/ViewProviderGeometryObject.cpp b/src/Gui/ViewProviderGeometryObject.cpp
index 7ffaf7bb4a..03102539b1 100644
--- a/src/Gui/ViewProviderGeometryObject.cpp
+++ b/src/Gui/ViewProviderGeometryObject.cpp
@@ -56,8 +56,6 @@ PROPERTY_SOURCE(Gui::ViewProviderGeometryObject, Gui::ViewProviderDragger)
 const App::PropertyIntegerConstraint::Constraints intPercent = {0, 100, 5};
 
 ViewProviderGeometryObject::ViewProviderGeometryObject()
-    : pcBoundSwitch(nullptr)
-    , pcBoundColor(nullptr)
 {
     ParameterGrp::handle hGrp = App::GetApplication().GetParameterGroupByPath("User parameter:BaseApp/Preferences/View");
     bool randomColor = hGrp->GetBool("RandomColor", false);
diff --git a/src/Gui/ViewProviderGeometryObject.h b/src/Gui/ViewProviderGeometryObject.h
index 0b16849284..34fb86f0f0 100644
--- a/src/Gui/ViewProviderGeometryObject.h
+++ b/src/Gui/ViewProviderGeometryObject.h
@@ -95,10 +95,10 @@ protected:
     virtual unsigned long getBoundColor() const;
 
 protected:
-    SoMaterial       * pcShapeMaterial;
-    SoFCBoundingBox  * pcBoundingBox;
-    SoSwitch         * pcBoundSwitch;
-    SoBaseColor      * pcBoundColor;
+    SoMaterial       * pcShapeMaterial{nullptr};
+    SoFCBoundingBox  * pcBoundingBox{nullptr};
+    SoSwitch         * pcBoundSwitch{nullptr};
+    SoBaseColor      * pcBoundColor{nullptr};
 };
 
 } // namespace Gui
diff --git a/src/Gui/ViewProviderGroupExtension.cpp b/src/Gui/ViewProviderGroupExtension.cpp
index 55178bf0f1..45ce98d452 100644
--- a/src/Gui/ViewProviderGroupExtension.cpp
+++ b/src/Gui/ViewProviderGroupExtension.cpp
@@ -43,7 +43,7 @@ using namespace Gui;
 
 EXTENSION_PROPERTY_SOURCE(Gui::ViewProviderGroupExtension, Gui::ViewProviderExtension)
 
-ViewProviderGroupExtension::ViewProviderGroupExtension()  : guard(false)
+ViewProviderGroupExtension::ViewProviderGroupExtension()
 {
     initExtensionType(ViewProviderGroupExtension::getExtensionClassTypeId());
 }
diff --git a/src/Gui/ViewProviderGroupExtension.h b/src/Gui/ViewProviderGroupExtension.h
index 11bbd531e6..882d96c0f4 100644
--- a/src/Gui/ViewProviderGroupExtension.h
+++ b/src/Gui/ViewProviderGroupExtension.h
@@ -52,7 +52,7 @@ public:
     bool extensionOnDelete(const std::vector<std::string> &) override;
 
 private:
-    bool guard;
+    bool guard{false};
     std::vector<ViewProvider*> nodes;
 };
 
diff --git a/src/Gui/ViewProviderPythonFeature.cpp b/src/Gui/ViewProviderPythonFeature.cpp
index 31f07284d6..4f7670d7db 100644
--- a/src/Gui/ViewProviderPythonFeature.cpp
+++ b/src/Gui/ViewProviderPythonFeature.cpp
@@ -57,7 +57,8 @@ namespace sp = std::placeholders;
 
 ViewProviderPythonFeatureImp::ViewProviderPythonFeatureImp(
         ViewProviderDocumentObject* vp, App::PropertyPythonObject &proxy)
-  : object(vp), Proxy(proxy), has__object__(false)
+  : object(vp)
+  , Proxy(proxy)
 {
 }
 
diff --git a/src/Gui/ViewProviderPythonFeature.h b/src/Gui/ViewProviderPythonFeature.h
index 7c6911386a..d074f5198b 100644
--- a/src/Gui/ViewProviderPythonFeature.h
+++ b/src/Gui/ViewProviderPythonFeature.h
@@ -129,7 +129,7 @@ public:
 private:
     ViewProviderDocumentObject* object;
     App::PropertyPythonObject &Proxy;
-    bool has__object__;
+    bool has__object__{false};
 
 #define FC_PY_VIEW_OBJECT \
     FC_PY_ELEMENT(getIcon) \
@@ -199,7 +199,7 @@ class ViewProviderPythonFeatureT : public ViewProviderT
 
 public:
     /// constructor.
-    ViewProviderPythonFeatureT() : _attached(false) {
+    ViewProviderPythonFeatureT() {
         ADD_PROPERTY(Proxy,(Py::Object()));
         imp = new ViewProviderPythonFeatureImp(this,Proxy);
     }
@@ -619,7 +619,7 @@ private:
     App::PropertyPythonObject Proxy;
     mutable std::string defaultMode;
     std::string viewerMode;
-    bool _attached;
+    bool _attached{false};
 };
 
 // Special Feature-Python classes
diff --git a/src/Gui/WaitCursor.cpp b/src/Gui/WaitCursor.cpp
index 4d0f4a4d08..3d548b43b8 100644
--- a/src/Gui/WaitCursor.cpp
+++ b/src/Gui/WaitCursor.cpp
@@ -53,14 +53,14 @@ protected:
 private:
     WaitCursorP(); // Disable constructor
     static WaitCursorP* _instance;
-    bool isOn;
-    WaitCursor::FilterEventsFlags flags;
+    bool isOn{false};
+    WaitCursor::FilterEventsFlags flags{WaitCursor::AllEvents};
 };
 } // namespace Gui
 
 WaitCursorP* WaitCursorP::_instance = nullptr;
 
-WaitCursorP::WaitCursorP() : QObject(nullptr), isOn(false), flags(WaitCursor::AllEvents)
+WaitCursorP::WaitCursorP() : QObject(nullptr)
 {
 }
 
diff --git a/src/Gui/Widgets.cpp b/src/Gui/Widgets.cpp
index b5caafe9e9..6bb50af393 100644
--- a/src/Gui/Widgets.cpp
+++ b/src/Gui/Widgets.cpp
@@ -618,23 +618,12 @@ struct ColorButtonP
 {
     QColor old, col;
     QPointer<QColorDialog> cd;
-    bool allowChange;
-    bool autoChange;
-    bool drawFrame;
-    bool allowTransparency;
-    bool modal;
-    bool dirty;
-
-    ColorButtonP()
-        : cd(nullptr)
-        , allowChange(true)
-        , autoChange(false)
-        , drawFrame(true)
-        , allowTransparency(false)
-        , modal(true)
-        , dirty(true)
-    {
-    }
+    bool allowChange{true};
+    bool autoChange{false};
+    bool drawFrame{true};
+    bool allowTransparency{false};
+    bool modal{true};
+    bool dirty{true};
 };
 }
 
diff --git a/src/Gui/Workbench.cpp b/src/Gui/Workbench.cpp
index 67331700b7..c1d65aa3aa 100644
--- a/src/Gui/Workbench.cpp
+++ b/src/Gui/Workbench.cpp
@@ -1021,10 +1021,7 @@ ToolBarItem* TestWorkbench::setupCommandBars() const
 
 TYPESYSTEM_SOURCE_ABSTRACT(Gui::PythonBaseWorkbench, Gui::Workbench)
 
-PythonBaseWorkbench::PythonBaseWorkbench()
-  : _menuBar(nullptr), _contextMenu(nullptr), _toolBar(nullptr), _commandBar(nullptr), _workbenchPy(nullptr)
-{
-}
+PythonBaseWorkbench::PythonBaseWorkbench() = default;
 
 PythonBaseWorkbench::~PythonBaseWorkbench()
 {
diff --git a/src/Gui/Workbench.h b/src/Gui/Workbench.h
index d6e3ccc3c1..46fe9038b1 100644
--- a/src/Gui/Workbench.h
+++ b/src/Gui/Workbench.h
@@ -289,11 +289,11 @@ protected:
     DockWindowItems* setupDockWindows() const override;
 
 protected:
-    MenuItem* _menuBar;
-    MenuItem* _contextMenu;
-    ToolBarItem* _toolBar;
-    ToolBarItem* _commandBar;
-    Base::PyObjectBase* _workbenchPy;
+    MenuItem* _menuBar{nullptr};
+    MenuItem* _contextMenu{nullptr};
+    ToolBarItem* _toolBar{nullptr};
+    ToolBarItem* _commandBar{nullptr};
+    Base::PyObjectBase* _workbenchPy{nullptr};
 };
 
 class GuiExport PythonBlankWorkbench : public PythonBaseWorkbench
diff --git a/src/Gui/WorkbenchManager.cpp b/src/Gui/WorkbenchManager.cpp
index 83dd266154..af9dc5dbda 100644
--- a/src/Gui/WorkbenchManager.cpp
+++ b/src/Gui/WorkbenchManager.cpp
@@ -48,9 +48,7 @@ void WorkbenchManager::destruct()
     _instance = nullptr;
 }
 
-WorkbenchManager::WorkbenchManager() : _activeWorkbench(nullptr)
-{
-}
+WorkbenchManager::WorkbenchManager() = default;
 
 WorkbenchManager::~WorkbenchManager()
 {
diff --git a/src/Gui/WorkbenchManager.h b/src/Gui/WorkbenchManager.h
index f7482ffc43..f5818c1fb8 100644
--- a/src/Gui/WorkbenchManager.h
+++ b/src/Gui/WorkbenchManager.h
@@ -25,6 +25,9 @@
 #define GUI_WORKBENCHMANAGER_H
 
 #include <list>
+#include <map>
+#include <string>
+#include <FCGlobal.h>
 
 namespace Gui {
 
@@ -67,7 +70,7 @@ protected:
 
 private:
     static WorkbenchManager* _instance;
-    Workbench*  _activeWorkbench;
+    Workbench*  _activeWorkbench{nullptr};
     std::map<std::string, Workbench*> _workbenches;
 };