diff --git a/common/dialogs/dialog_text_entry.cpp b/common/dialogs/dialog_text_entry.cpp
index 1a0c902ddc..9a47526baa 100644
--- a/common/dialogs/dialog_text_entry.cpp
+++ b/common/dialogs/dialog_text_entry.cpp
@@ -48,7 +48,7 @@ void WX_TEXT_ENTRY_DIALOG::SetTextValidator( const wxTextValidator& validator )
 }
 
 
-wxString WX_TEXT_ENTRY_DIALOG::GetValue()
+wxString WX_TEXT_ENTRY_DIALOG::GetValue() const
 {
     return m_textCtrl->GetValue();
 }
diff --git a/common/dialogs/dialog_text_entry.h b/common/dialogs/dialog_text_entry.h
index ad50c0b488..24291f43d3 100644
--- a/common/dialogs/dialog_text_entry.h
+++ b/common/dialogs/dialog_text_entry.h
@@ -44,7 +44,7 @@ public:
     void SetTextValidator( wxTextValidatorStyle style );
     void SetTextValidator( const wxTextValidator& validator );
 
-    wxString GetValue();
+    wxString GetValue() const;
 };
 
 #endif      // _DIALOG_TEXT_ENTRY_H_
diff --git a/common/eda_size_ctrl.cpp b/common/eda_size_ctrl.cpp
index d076cbfcee..2e1e897f5f 100644
--- a/common/eda_size_ctrl.cpp
+++ b/common/eda_size_ctrl.cpp
@@ -62,7 +62,7 @@ EDA_POSITION_CTRL::~EDA_POSITION_CTRL()
 
 /* Returns (in internal units) to coordinate between (in user units)
  */
-wxPoint EDA_POSITION_CTRL::GetValue()
+wxPoint EDA_POSITION_CTRL::GetValue() const
 {
     return wxPoint( ValueFromString( m_UserUnit, m_FramePosX->GetValue() ),
                     ValueFromString( m_UserUnit, m_FramePosY->GetValue() ) );
@@ -93,7 +93,7 @@ EDA_SIZE_CTRL::EDA_SIZE_CTRL( wxWindow* parent, const wxString& title, const wxS
 }
 
 
-wxSize EDA_SIZE_CTRL::GetValue()
+wxSize EDA_SIZE_CTRL::GetValue() const
 {
     wxPoint pos = EDA_POSITION_CTRL::GetValue();
 
diff --git a/common/eda_text.cpp b/common/eda_text.cpp
index dfe6aa4a1c..e230f4be60 100644
--- a/common/eda_text.cpp
+++ b/common/eda_text.cpp
@@ -481,7 +481,7 @@ void EDA_TEXT::printOneLineOfText( RENDER_SETTINGS* aSettings, const wxPoint& aO
 }
 
 
-wxString EDA_TEXT::GetTextStyleName()
+wxString EDA_TEXT::GetTextStyleName() const
 {
     int style = 0;
 
diff --git a/common/origin_transforms.cpp b/common/origin_transforms.cpp
index 4972312353..92fe01c3a9 100644
--- a/common/origin_transforms.cpp
+++ b/common/origin_transforms.cpp
@@ -33,37 +33,37 @@ ORIGIN_TRANSFORMS::~ORIGIN_TRANSFORMS()
 
 
 int ORIGIN_TRANSFORMS::ToDisplay( int           aValue,
-                                  COORD_TYPES_T aCoordType )
+                                  COORD_TYPES_T aCoordType ) const
 {
     return static_cast<int>( ToDisplay( static_cast<long long int>( aValue ), aCoordType ) );
 }
 
 long long int ORIGIN_TRANSFORMS::ToDisplay( long long int aValue,
-                                            COORD_TYPES_T aCoordType )
+                                            COORD_TYPES_T aCoordType ) const
 {
     return aValue;
 }
 
 double ORIGIN_TRANSFORMS::ToDisplay( double        aValue,
-                                     COORD_TYPES_T aCoordType )
+                                     COORD_TYPES_T aCoordType ) const
 {
     return aValue;
 }
 
 int ORIGIN_TRANSFORMS::FromDisplay( int           aValue,
-                                    COORD_TYPES_T aCoordType )
+                                    COORD_TYPES_T aCoordType ) const
 {
     return static_cast<int>( FromDisplay( static_cast<long long int>( aValue ), aCoordType ) );
 }
 
 long long int ORIGIN_TRANSFORMS::FromDisplay( long long int aValue,
-                                              COORD_TYPES_T aCoordType )
+                                              COORD_TYPES_T aCoordType ) const
 {
     return aValue;
 }
 
 double ORIGIN_TRANSFORMS::FromDisplay( double        aValue,
-                                       COORD_TYPES_T aCoordType )
+                                       COORD_TYPES_T aCoordType ) const
 {
     return aValue;
 }
diff --git a/common/tool/action_manager.cpp b/common/tool/action_manager.cpp
index 0310726eca..229125b171 100644
--- a/common/tool/action_manager.cpp
+++ b/common/tool/action_manager.cpp
@@ -225,7 +225,7 @@ bool ACTION_MANAGER::RunHotKey( int aHotKey ) const
 }
 
 
-const std::map<std::string, TOOL_ACTION*>& ACTION_MANAGER::GetActions()
+const std::map<std::string, TOOL_ACTION*>& ACTION_MANAGER::GetActions() const
 {
     return m_actionNameIndex;
 }
diff --git a/common/view/view.cpp b/common/view/view.cpp
index 797c62fd8a..d29a914c88 100644
--- a/common/view/view.cpp
+++ b/common/view/view.cpp
@@ -1504,13 +1504,13 @@ bool VIEW::IsVisible( const VIEW_ITEM* aItem ) const
 }
 
 
-void VIEW::Update( VIEW_ITEM* aItem )
+void VIEW::Update( const VIEW_ITEM* aItem ) const
 {
     Update( aItem, ALL );
 }
 
 
-void VIEW::Update( VIEW_ITEM* aItem, int aUpdateFlags )
+void VIEW::Update( const VIEW_ITEM* aItem, int aUpdateFlags ) const
 {
     VIEW_ITEM_DATA* viewData = aItem->viewPrivData();
 
diff --git a/eeschema/dialogs/dialog_fields_editor_global.cpp b/eeschema/dialogs/dialog_fields_editor_global.cpp
index acf7d482cb..da9491fb65 100644
--- a/eeschema/dialogs/dialog_fields_editor_global.cpp
+++ b/eeschema/dialogs/dialog_fields_editor_global.cpp
@@ -263,13 +263,13 @@ public:
             return GetValue( m_rows[ aRow ], aCol );
     }
 
-    std::vector<SCH_REFERENCE> GetRowReferences( int aRow )
+    std::vector<SCH_REFERENCE> GetRowReferences( int aRow ) const
     {
         wxCHECK( aRow < (int)m_rows.size(), std::vector<SCH_REFERENCE>() );
         return m_rows[ aRow ].m_Refs;
     }
 
-    wxString GetValue( DATA_MODEL_ROW& group, int aCol )
+    wxString GetValue( const DATA_MODEL_ROW& group, int aCol )
     {
         std::vector<SCH_REFERENCE> references;
         wxString                   fieldValue;
diff --git a/eeschema/fields_grid_table.cpp b/eeschema/fields_grid_table.cpp
index fe5a252f01..7c83865264 100644
--- a/eeschema/fields_grid_table.cpp
+++ b/eeschema/fields_grid_table.cpp
@@ -613,7 +613,7 @@ void FIELDS_GRID_TRICKS::doPopupSelection( wxCommandEvent& event )
 
 
 template <class T>
-wxString FIELDS_GRID_TABLE<T>::StringFromBool( bool aValue )
+wxString FIELDS_GRID_TABLE<T>::StringFromBool( bool aValue ) const
 {
     if( aValue )
         return wxT( "1" );
@@ -623,7 +623,7 @@ wxString FIELDS_GRID_TABLE<T>::StringFromBool( bool aValue )
 
 
 template <class T>
-bool FIELDS_GRID_TABLE<T>::BoolFromString( wxString aValue )
+bool FIELDS_GRID_TABLE<T>::BoolFromString( wxString aValue ) const
 {
     if( aValue == "1" )
     {
diff --git a/eeschema/fields_grid_table.h b/eeschema/fields_grid_table.h
index c25c68de27..a9643a36d9 100644
--- a/eeschema/fields_grid_table.h
+++ b/eeschema/fields_grid_table.h
@@ -96,8 +96,8 @@ public:
     void SetValue( int aRow, int aCol, const wxString &aValue ) override;
     void SetValueAsBool( int aRow, int aCol, bool aValue ) override;
 
-    wxString StringFromBool( bool aValue );
-    bool BoolFromString( wxString aValue );
+    wxString StringFromBool( bool aValue ) const;
+    bool BoolFromString( wxString aValue ) const;
 
 protected:
     void initGrid( DIALOG_SHIM* aDialog );
diff --git a/eeschema/lib_arc.h b/eeschema/lib_arc.h
index f598d2be68..305eaf451c 100644
--- a/eeschema/lib_arc.h
+++ b/eeschema/lib_arc.h
@@ -65,7 +65,7 @@ public:
         return wxT( "LIB_ARC" );
     }
 
-    wxString GetTypeName() override
+    wxString GetTypeName() const override
     {
         return _( "Arc" );
     }
diff --git a/eeschema/lib_bezier.h b/eeschema/lib_bezier.h
index a9095cd6d6..9c6a03ba60 100644
--- a/eeschema/lib_bezier.h
+++ b/eeschema/lib_bezier.h
@@ -49,7 +49,7 @@ public:
         return wxT( "LIB_BEZIER" );
     }
 
-    wxString GetTypeName() override
+    wxString GetTypeName() const override
     {
         return _( "Bezier" );
     }
diff --git a/eeschema/lib_circle.h b/eeschema/lib_circle.h
index a45d1dc2f3..8cabd5f6dd 100644
--- a/eeschema/lib_circle.h
+++ b/eeschema/lib_circle.h
@@ -48,7 +48,7 @@ public:
         return wxT( "LIB_CIRCLE" );
     }
 
-    wxString GetTypeName() override
+    wxString GetTypeName() const override
     {
         return _( "Circle" );
     }
diff --git a/eeschema/lib_field.h b/eeschema/lib_field.h
index 7d18a293ba..56e2650743 100644
--- a/eeschema/lib_field.h
+++ b/eeschema/lib_field.h
@@ -97,7 +97,7 @@ public:
         return wxT( "LIB_FIELD" );
     }
 
-    wxString GetTypeName() override
+    wxString GetTypeName() const override
     {
         return _( "Field" );
     }
diff --git a/eeschema/lib_item.h b/eeschema/lib_item.h
index 38ffdae449..7840018000 100644
--- a/eeschema/lib_item.h
+++ b/eeschema/lib_item.h
@@ -120,7 +120,7 @@ public:
      * Provide a user-consumable name of the object type.  Perform localization when
      * called so that run-time language selection works.
      */
-    virtual wxString GetTypeName() = 0;
+    virtual wxString GetTypeName() const = 0;
 
     /**
      * Begin drawing a component library draw item at \a aPosition.
diff --git a/eeschema/lib_pin.h b/eeschema/lib_pin.h
index c2b2dff8a2..1b1f352338 100644
--- a/eeschema/lib_pin.h
+++ b/eeschema/lib_pin.h
@@ -117,7 +117,7 @@ public:
         return wxT( "LIB_PIN" );
     }
 
-    wxString GetTypeName() override
+    wxString GetTypeName() const override
     {
         return _( "Pin" );
     }
diff --git a/eeschema/lib_polyline.h b/eeschema/lib_polyline.h
index 7918cfe952..1f7046118a 100644
--- a/eeschema/lib_polyline.h
+++ b/eeschema/lib_polyline.h
@@ -48,7 +48,7 @@ public:
         return wxT( "LIB_POLYLINE" );
     }
 
-    wxString GetTypeName() override
+    wxString GetTypeName() const override
     {
         return _( "PolyLine" );
     }
diff --git a/eeschema/lib_rectangle.h b/eeschema/lib_rectangle.h
index 684e6ea66c..fbe57f8917 100644
--- a/eeschema/lib_rectangle.h
+++ b/eeschema/lib_rectangle.h
@@ -49,7 +49,7 @@ public:
         return wxT( "LIB_RECTANGLE" );
     }
 
-    wxString GetTypeName() override
+    wxString GetTypeName() const override
     {
         return _( "Rectangle" );
     }
diff --git a/eeschema/lib_text.h b/eeschema/lib_text.h
index 2652d94cba..9b1f306958 100644
--- a/eeschema/lib_text.h
+++ b/eeschema/lib_text.h
@@ -54,7 +54,7 @@ public:
         return wxT( "LIB_TEXT" );
     }
 
-    wxString GetTypeName() override
+    wxString GetTypeName() const override
     {
         return _( "Text" );
     }
diff --git a/eeschema/sch_rtree.h b/eeschema/sch_rtree.h
index 19669cdebc..7e2549fdc9 100644
--- a/eeschema/sch_rtree.h
+++ b/eeschema/sch_rtree.h
@@ -119,7 +119,7 @@ public:
      * @param aRobust If true, search the whole tree, not just the bounding box
      * @return true if the item definitely exists, false if it does not exist within bbox
      */
-    bool contains( SCH_ITEM* aItem, bool aRobust = false )
+    bool contains( const SCH_ITEM* aItem, bool aRobust = false ) const
     {
         const EDA_RECT& bbox    = aItem->GetBoundingBox();
         const int       type    = int( aItem->Type() );
@@ -158,12 +158,12 @@ public:
      * Returns the number of items in the tree
      * @return number of elements in the tree;
      */
-    size_t size()
+    size_t size() const
     {
         return m_count;
     }
 
-    bool empty()
+    bool empty() const
     {
         return m_count == 0;
     }
diff --git a/include/class_pcb_group.h b/include/class_pcb_group.h
index 2ea9d2ce7c..24240c0c21 100644
--- a/include/class_pcb_group.h
+++ b/include/class_pcb_group.h
@@ -178,7 +178,7 @@ public:
      *
      * @param aCommit is the commit to add the children to.
      */
-    void AddChildrenToCommit( BOARD_COMMIT& aCommit )
+    void AddChildrenToCommit( BOARD_COMMIT& aCommit ) const
     {
         RunOnChildren( [&]( BOARD_ITEM* bItem )
                        {
@@ -191,7 +191,7 @@ public:
      * Note that this function should not add or remove items to the group
      * @param aFunction is the function to be invoked.
      */
-    void RunOnChildren( const std::function<void ( BOARD_ITEM* )>& aFunction );
+    void RunOnChildren( const std::function<void ( BOARD_ITEM* )>& aFunction ) const;
 
     /**
      * Invokes a function on all descendents of the group.
@@ -199,7 +199,7 @@ public:
      * groups.
      * @param aFunction is the function to be invoked.
      */
-    void RunOnDescendants( const std::function<void( BOARD_ITEM* )>& aFunction );
+    void RunOnDescendants( const std::function<void( BOARD_ITEM* )>& aFunction ) const;
 
 private:
     std::unordered_set<BOARD_ITEM*> m_items;     // Members of the group
diff --git a/include/dialog_helpers.h b/include/dialog_helpers.h
index 44b1374036..a192cec39b 100644
--- a/include/dialog_helpers.h
+++ b/include/dialog_helpers.h
@@ -117,7 +117,7 @@ public:
 
     void    Enable( bool x_win_on, bool y_win_on );
     void    SetValue( int x_value, int y_value );
-    wxPoint GetValue();
+    wxPoint GetValue() const;
 };
 
 
@@ -132,7 +132,7 @@ public:
                    EDA_UNITS user_unit, wxBoxSizer* BoxSizer );
 
     ~EDA_SIZE_CTRL() { }
-    wxSize GetValue();
+    wxSize GetValue() const;
 };
 
 
diff --git a/include/eda_rect.h b/include/eda_rect.h
index 0508db41db..362b4b51ed 100644
--- a/include/eda_rect.h
+++ b/include/eda_rect.h
@@ -106,7 +106,7 @@ public:
      * @brief GetSizeMax
      * @return the max size dimension
      */
-    int GetSizeMax() const { return ( m_Size.x > m_Size.y )?m_Size.x:m_Size.y; }
+    int GetSizeMax() const { return ( m_Size.x > m_Size.y ) ? m_Size.x : m_Size.y; }
 
     int GetX() const { return m_Pos.x; }
     int GetY() const { return m_Pos.y; }
diff --git a/include/eda_text.h b/include/eda_text.h
index f0ba647293..c10268f068 100644
--- a/include/eda_text.h
+++ b/include/eda_text.h
@@ -351,7 +351,7 @@ public:
     /**
      * @return a wxString with the style name( Normal, Italic, Bold, Bold+Italic)
      */
-    wxString GetTextStyleName();
+    wxString GetTextStyleName() const;
 
     /**
      * Populate \a aPositions with the position of each line of
diff --git a/include/gbr_netlist_metadata.h b/include/gbr_netlist_metadata.h
index 82b6edf48f..ce82d8be26 100644
--- a/include/gbr_netlist_metadata.h
+++ b/include/gbr_netlist_metadata.h
@@ -107,7 +107,7 @@ public:
 
     void Clear() { clear(); }
 
-    const wxString& GetValue() { return m_field; }
+    const wxString& GetValue() const { return m_field; }
 
     void SetField( const wxString& aField, bool aUseUTF8, bool aEscapeString )
     {
@@ -116,7 +116,7 @@ public:
         m_escapeString = aEscapeString;
     }
 
-    bool IsEmpty() { return m_field.IsEmpty(); }
+    bool IsEmpty() const { return m_field.IsEmpty(); }
 
     std::string GetGerberString();
 
diff --git a/include/libeval_compiler/libeval_compiler.h b/include/libeval_compiler/libeval_compiler.h
index ab6bf07f19..009a637cec 100644
--- a/include/libeval_compiler/libeval_compiler.h
+++ b/include/libeval_compiler/libeval_compiler.h
@@ -254,7 +254,7 @@ public:
     VAR_REF() {};
     virtual ~VAR_REF() {};
 
-    virtual VAR_TYPE_T GetType() = 0;
+    virtual VAR_TYPE_T GetType() const = 0;
     virtual VALUE GetValue( CONTEXT* aCtx ) = 0;
 };
 
diff --git a/include/origin_transforms.h b/include/origin_transforms.h
index 9a4e808b73..244641dc0e 100644
--- a/include/origin_transforms.h
+++ b/include/origin_transforms.h
@@ -23,7 +23,7 @@
  */
 
 #ifndef ORIGIN_TRANSFORMS_H_
-#define ORIGIN_TRANSFORMS_H_ 1
+#define ORIGIN_TRANSFORMS_H_
 
 /**
  * A class to perform either relative or absolute display origin
@@ -61,28 +61,28 @@ public:
     // =============== Single-axis Transforms ===============
 
     virtual int ToDisplay( int           aValue,
-                           COORD_TYPES_T aCoordType );
+                           COORD_TYPES_T aCoordType ) const;
 
     virtual long long int ToDisplay( long long int aValue,
-                                     COORD_TYPES_T aCoordType );
+                                     COORD_TYPES_T aCoordType ) const;
 
     virtual double ToDisplay( double        aValue,
-                              COORD_TYPES_T aCoordType );
+                              COORD_TYPES_T aCoordType ) const;
 
     virtual int FromDisplay( int           aValue,
-                             COORD_TYPES_T aCoordType );
+                             COORD_TYPES_T aCoordType ) const;
 
     virtual long long int FromDisplay( long long int aValue,
-                                       COORD_TYPES_T aCoordType );
+                                       COORD_TYPES_T aCoordType ) const;
 
     virtual double FromDisplay( double        aValue,
-                                COORD_TYPES_T aCoordType );
+                                COORD_TYPES_T aCoordType ) const;
 
 
     // =============== Two-axis Transforms ===============
 
     template<class T>
-    T ToDisplayAbs( const T& aValue )
+    T ToDisplayAbs( const T& aValue ) const
     {
         T displayValue;
 
@@ -92,7 +92,7 @@ public:
     }
 
     template<class T>
-    T ToDisplayRel( const T& aValue )
+    T ToDisplayRel( const T& aValue ) const
     {
         T displayValue;
 
@@ -103,7 +103,7 @@ public:
 
 
     template<class T>
-    T FromDisplayAbs( const T& aValue )
+    T FromDisplayAbs( const T& aValue ) const
     {
         T displayValue;
 
@@ -113,7 +113,7 @@ public:
     }
 
     template<class T>
-    T FromDisplayRel( const T& aValue )
+    T FromDisplayRel( const T& aValue ) const
     {
         T displayValue;
 
diff --git a/include/tool/action_manager.h b/include/tool/action_manager.h
index 8b1d564f7b..a96575619a 100644
--- a/include/tool/action_manager.h
+++ b/include/tool/action_manager.h
@@ -110,7 +110,7 @@ public:
     /**
      * Get a list of currently-registered actions mapped by their name.
      */
-    const std::map<std::string, TOOL_ACTION*>& GetActions();
+    const std::map<std::string, TOOL_ACTION*>& GetActions() const;
 
     /**
      * Finds an action with a given name (if there is one available).
diff --git a/include/view/view.h b/include/view/view.h
index bc7b0196cd..e0ac202429 100644
--- a/include/view/view.h
+++ b/include/view/view.h
@@ -141,8 +141,8 @@ public:
      * @param aItem: the item to update.
      * @param aUpdateFlags: how much the object has changed.
      */
-    virtual void Update( VIEW_ITEM* aItem, int aUpdateFlags );
-    virtual void Update( VIEW_ITEM* aItem );
+    virtual void Update( const VIEW_ITEM* aItem, int aUpdateFlags ) const;
+    virtual void Update( const VIEW_ITEM* aItem ) const;
 
     /**
      * Function SetRequired()
diff --git a/include/view/view_rtree.h b/include/view/view_rtree.h
index 3f16c8777d..92e72564eb 100644
--- a/include/view/view_rtree.h
+++ b/include/view/view_rtree.h
@@ -77,7 +77,7 @@ public:
      * with aBounds.
      */
     template <class Visitor>
-    void Query( const BOX2I& aBounds, Visitor& aVisitor )    // const
+    void Query( const BOX2I& aBounds, Visitor& aVisitor ) const
     {
         int   mmin[2] = { aBounds.GetX(), aBounds.GetY() };
         int   mmax[2] = { aBounds.GetRight(), aBounds.GetBottom() };
diff --git a/include/widgets/bitmap_toggle.h b/include/widgets/bitmap_toggle.h
index 44d97a283d..9866df16e7 100644
--- a/include/widgets/bitmap_toggle.h
+++ b/include/widgets/bitmap_toggle.h
@@ -50,7 +50,7 @@ public:
     void SetValue( bool aValue );
 
     ///> Read the checkbox state
-    bool GetValue() { return m_checked; }
+    bool GetValue() const { return m_checked; }
 
 private:
     bool m_checked;
diff --git a/libs/kimath/include/geometry/shape_index.h b/libs/kimath/include/geometry/shape_index.h
index b0607875f6..3f06b23573 100644
--- a/libs/kimath/include/geometry/shape_index.h
+++ b/libs/kimath/include/geometry/shape_index.h
@@ -173,7 +173,7 @@ class SHAPE_INDEX
              * Checks if the iterator has reached the end.
              * @return true if it is in an invalid position (data finished)
              */
-            bool IsNull()
+            bool IsNull() const
             {
                 return iterator.IsNull();
             }
@@ -184,7 +184,7 @@ class SHAPE_INDEX
              * Checks if the iterator has not reached the end.
              * @return true if it is in an valid position (data not finished)
              */
-            bool IsNotNull()
+            bool IsNotNull() const
             {
                 return iterator.IsNotNull();
             }
@@ -275,7 +275,7 @@ class SHAPE_INDEX
          * @param aVisitor object to be invoked on every object contained in the search area.
          */
         template <class V>
-        int Query( const SHAPE *aShape, int aMinDistance, V& aVisitor, bool aExact )
+        int Query( const SHAPE *aShape, int aMinDistance, V& aVisitor) const
         {
             BOX2I box = aShape->BBox();
             box.Inflate( aMinDistance );
@@ -377,4 +377,4 @@ typename SHAPE_INDEX<T>::Iterator SHAPE_INDEX<T>::Begin()
     return Iterator( this );
 }
 
-#endif
+#endif /* __SHAPE_INDEX_H */
diff --git a/pcbnew/class_board.cpp b/pcbnew/class_board.cpp
index afef86ac26..c5be887e83 100644
--- a/pcbnew/class_board.cpp
+++ b/pcbnew/class_board.cpp
@@ -969,7 +969,7 @@ wxString BOARD::ConvertKIIDsToCrossReferences( const wxString& aSource )
 }
 
 
-unsigned BOARD::GetNodesCount( int aNet )
+unsigned BOARD::GetNodesCount( int aNet ) const
 {
     unsigned retval = 0;
 
@@ -1854,7 +1854,7 @@ bool BOARD::GetBoardPolygonOutlines( SHAPE_POLY_SET& aOutlines, wxString* aError
 }
 
 
-const std::vector<D_PAD*> BOARD::GetPads()
+const std::vector<D_PAD*> BOARD::GetPads() const
 {
     std::vector<D_PAD*> allPads;
 
@@ -1868,7 +1868,7 @@ const std::vector<D_PAD*> BOARD::GetPads()
 }
 
 
-unsigned BOARD::GetPadCount()
+unsigned BOARD::GetPadCount() const
 {
     unsigned retval = 0;
 
diff --git a/pcbnew/class_board.h b/pcbnew/class_board.h
index 47b8f08ad0..a301b621b9 100644
--- a/pcbnew/class_board.h
+++ b/pcbnew/class_board.h
@@ -680,7 +680,7 @@ public:
      * @param aNet Only count nodes belonging to this net
      * @return the number of pads members of nets (i.e. with netcode > 0)
      */
-    unsigned GetNodesCount( int aNet = -1 );
+    unsigned GetNodesCount( int aNet = -1 ) const;
 
     /**
      * @return the number of unconnected nets in the current ratsnest.
@@ -690,7 +690,7 @@ public:
     /**
      * @return the number of pads in board
      */
-    unsigned GetPadCount();
+    unsigned GetPadCount() const;
 
     /**
      * Return a reference to a list of all the pads.
@@ -700,7 +700,7 @@ public:
      *
      * @return D_PADS - a full list of pads
      */
-    const std::vector<D_PAD*> GetPads();
+    const std::vector<D_PAD*> GetPads() const;
 
     void BuildListOfNets()
     {
diff --git a/pcbnew/class_module.cpp b/pcbnew/class_module.cpp
index 5f4ffd3ccd..60ffaa342f 100644
--- a/pcbnew/class_module.cpp
+++ b/pcbnew/class_module.cpp
@@ -1063,7 +1063,7 @@ EDA_ITEM* MODULE::Clone() const
 }
 
 
-void MODULE::RunOnChildren( const std::function<void (BOARD_ITEM*)>& aFunction )
+void MODULE::RunOnChildren( const std::function<void (BOARD_ITEM*)>& aFunction ) const
 {
     try
     {
diff --git a/pcbnew/class_module.h b/pcbnew/class_module.h
index dead267f12..475843048c 100644
--- a/pcbnew/class_module.h
+++ b/pcbnew/class_module.h
@@ -594,7 +594,7 @@ public:
      * Note that this function should not add or remove items to the module
      * @param aFunction is the function to be invoked.
      */
-    void RunOnChildren( const std::function<void (BOARD_ITEM*)>& aFunction );
+    void RunOnChildren( const std::function<void (BOARD_ITEM*)>& aFunction ) const;
 
     /**
      * Returns a set of all layers that this module has drawings on similar to ViewGetLayers()
diff --git a/pcbnew/class_pcb_group.cpp b/pcbnew/class_pcb_group.cpp
index 11e40a372f..4f39e3a6eb 100644
--- a/pcbnew/class_pcb_group.cpp
+++ b/pcbnew/class_pcb_group.cpp
@@ -310,7 +310,7 @@ void PCB_GROUP::GetMsgPanelInfo( EDA_DRAW_FRAME* aFrame, std::vector<MSG_PANEL_I
 }
 
 
-void PCB_GROUP::RunOnChildren( const std::function<void( BOARD_ITEM* )>& aFunction )
+void PCB_GROUP::RunOnChildren( const std::function<void( BOARD_ITEM* )>& aFunction ) const
 {
     try
     {
@@ -324,7 +324,7 @@ void PCB_GROUP::RunOnChildren( const std::function<void( BOARD_ITEM* )>& aFuncti
 }
 
 
-void PCB_GROUP::RunOnDescendants( const std::function<void( BOARD_ITEM* )>& aFunction )
+void PCB_GROUP::RunOnDescendants( const std::function<void( BOARD_ITEM* )>& aFunction ) const
 {
     try
     {
diff --git a/pcbnew/class_track.cpp b/pcbnew/class_track.cpp
index 673bf7d2bb..8b79ebd7e7 100644
--- a/pcbnew/class_track.cpp
+++ b/pcbnew/class_track.cpp
@@ -713,7 +713,7 @@ void VIA::GetMsgPanelInfo( EDA_DRAW_FRAME* aFrame, std::vector<MSG_PANEL_ITEM>&
 }
 
 
-void TRACK::GetMsgPanelInfoBase_Common( EDA_DRAW_FRAME* aFrame, std::vector<MSG_PANEL_ITEM>& aList )
+void TRACK::GetMsgPanelInfoBase_Common( EDA_DRAW_FRAME* aFrame, std::vector<MSG_PANEL_ITEM>& aList ) const
 {
     wxString msg;
 
diff --git a/pcbnew/class_track.h b/pcbnew/class_track.h
index e74c4f8bcb..4c9949ba35 100644
--- a/pcbnew/class_track.h
+++ b/pcbnew/class_track.h
@@ -259,7 +259,7 @@ public:
 #endif
 
 protected:
-    void GetMsgPanelInfoBase_Common( EDA_DRAW_FRAME* aFrame, std::vector<MSG_PANEL_ITEM>& aList );
+    void GetMsgPanelInfoBase_Common( EDA_DRAW_FRAME* aFrame, std::vector<MSG_PANEL_ITEM>& aList ) const;
 
 
     int         m_Width;            ///< Thickness of track, or via diameter
diff --git a/pcbnew/connectivity/connectivity_rtree.h b/pcbnew/connectivity/connectivity_rtree.h
index c57a566b8b..76ff2689db 100644
--- a/pcbnew/connectivity/connectivity_rtree.h
+++ b/pcbnew/connectivity/connectivity_rtree.h
@@ -107,7 +107,7 @@ public:
      * with aBounds.
      */
     template <class Visitor>
-    void Query( const BOX2I& aBounds, const LAYER_RANGE& aRange, Visitor& aVisitor )
+    void Query( const BOX2I& aBounds, const LAYER_RANGE& aRange, Visitor& aVisitor ) const
     {
         const int   mmin[3] = { aRange.Start(), aBounds.GetX(), aBounds.GetY() };
         const int   mmax[3] = { aRange.End(), aBounds.GetRight(), aBounds.GetBottom() };
diff --git a/pcbnew/dialogs/dialog_get_footprint_by_name.h b/pcbnew/dialogs/dialog_get_footprint_by_name.h
index 234bce7119..17f10bc167 100644
--- a/pcbnew/dialogs/dialog_get_footprint_by_name.h
+++ b/pcbnew/dialogs/dialog_get_footprint_by_name.h
@@ -55,7 +55,7 @@ public:
     }
 
     // returns the selected text (fp reference)
-    const wxString GetValue()
+    const wxString GetValue() const
     {
         return m_SearchTextCtrl->GetValue();
     }
diff --git a/pcbnew/dialogs/wizard_3DShape_Libs_downloader.h b/pcbnew/dialogs/wizard_3DShape_Libs_downloader.h
index 58a1e44fd7..dfcb6f8402 100644
--- a/pcbnew/dialogs/wizard_3DShape_Libs_downloader.h
+++ b/pcbnew/dialogs/wizard_3DShape_Libs_downloader.h
@@ -95,7 +95,7 @@ protected:
     }
 
     ///> Gets the current target for downloaded libraries
-    inline wxString getDownloadDir()
+    inline wxString getDownloadDir() const
     {
         return m_downloadDir->GetValue();
     }
diff --git a/pcbnew/drc/drc_rtree.h b/pcbnew/drc/drc_rtree.h
index e20773c7a6..5facb3ecaf 100644
--- a/pcbnew/drc/drc_rtree.h
+++ b/pcbnew/drc/drc_rtree.h
@@ -240,7 +240,7 @@ public:
     bool CheckColliding( SHAPE* aRefShape,
                          PCB_LAYER_ID aTargetLayer,
                          int aClearance = 0,
-                         std::function<bool( BOARD_ITEM*)> aFilter = nullptr )
+                         std::function<bool( BOARD_ITEM*)> aFilter = nullptr ) const
     {
         BOX2I box = aRefShape->BBox();
         box.Inflate( aClearance );
@@ -276,7 +276,7 @@ public:
                         PCB_LAYER_ID aTargetLayer,
                         std::function<bool( BOARD_ITEM*)> aFilter = nullptr,
                         std::function<bool( BOARD_ITEM*, int)> aVisitor = nullptr,
-                        int aClearance = 0 )
+                        int aClearance = 0 ) const
     {
         // keep track of BOARD_ITEMs that have been already found to collide (some items
         // might be build of COMPOUND/triangulated shapes and a single subshape collision
@@ -344,7 +344,7 @@ public:
                                                  ITEM_WITH_SHAPE*, ITEM_WITH_SHAPE*,
                                                  bool* aCollision )> aVisitor,
                              int aMaxClearance,
-                             std::function<bool(int, int )> aProgressReporter )
+                             std::function<bool(int, int )> aProgressReporter ) const
     {
         std::vector< PAIR_INFO > pairsToVisit;
 
@@ -463,12 +463,12 @@ public:
      * Returns the number of items in the tree
      * @return number of elements in the tree;
      */
-    size_t size()
+    size_t size() const
     {
         return m_count;
     }
 
-    bool empty()
+    bool empty() const
     {
         return m_count == 0;
     }
diff --git a/pcbnew/pcb_expr_evaluator.cpp b/pcbnew/pcb_expr_evaluator.cpp
index 721f36c731..9489eba2a2 100644
--- a/pcbnew/pcb_expr_evaluator.cpp
+++ b/pcbnew/pcb_expr_evaluator.cpp
@@ -488,9 +488,9 @@ void PCB_EXPR_BUILTIN_FUNCTIONS::RegisterAllFunctions()
 }
 
 
-BOARD_ITEM* PCB_EXPR_VAR_REF::GetObject( LIBEVAL::CONTEXT* aCtx ) const
+BOARD_ITEM* PCB_EXPR_VAR_REF::GetObject( const LIBEVAL::CONTEXT* aCtx ) const
 {
-    wxASSERT( dynamic_cast<PCB_EXPR_CONTEXT*>( aCtx ) );
+    wxASSERT( dynamic_cast<const PCB_EXPR_CONTEXT*>( aCtx ) );
 
     const PCB_EXPR_CONTEXT* ctx = static_cast<const PCB_EXPR_CONTEXT*>( aCtx );
     BOARD_ITEM*             item  = ctx->GetItem( m_itemIndex );
diff --git a/pcbnew/pcb_expr_evaluator.h b/pcbnew/pcb_expr_evaluator.h
index f5640f52bd..2e282f541b 100644
--- a/pcbnew/pcb_expr_evaluator.h
+++ b/pcbnew/pcb_expr_evaluator.h
@@ -97,7 +97,7 @@ public:
     bool IsEnum() const { return m_isEnum; }
 
     void SetType( LIBEVAL::VAR_TYPE_T type ) { m_type = type; }
-    LIBEVAL::VAR_TYPE_T GetType() override { return m_type; }
+    LIBEVAL::VAR_TYPE_T GetType() const override { return m_type; }
 
     void AddAllowedClass( TYPE_ID type_hash, PROPERTY_BASE* prop )
     {
@@ -106,7 +106,7 @@ public:
 
     virtual LIBEVAL::VALUE GetValue( LIBEVAL::CONTEXT* aCtx ) override;
 
-    BOARD_ITEM* GetObject( LIBEVAL::CONTEXT* aCtx ) const;
+    BOARD_ITEM* GetObject( const LIBEVAL::CONTEXT* aCtx ) const;
 
 private:
     std::unordered_map<TYPE_ID, PROPERTY_BASE*> m_matchingTypes;
diff --git a/pcbnew/pcb_origin_transforms.cpp b/pcbnew/pcb_origin_transforms.cpp
index f491ffd6c2..d35be4f462 100644
--- a/pcbnew/pcb_origin_transforms.cpp
+++ b/pcbnew/pcb_origin_transforms.cpp
@@ -39,7 +39,7 @@ PCB_ORIGIN_TRANSFORMS::~PCB_ORIGIN_TRANSFORMS()
 {}
 
 long long int PCB_ORIGIN_TRANSFORMS::ToDisplay( long long int aValue,
-                                                COORD_TYPES_T aCoordType )
+                                                COORD_TYPES_T aCoordType ) const
 {
     long long int value = aValue;
 
@@ -57,7 +57,7 @@ long long int PCB_ORIGIN_TRANSFORMS::ToDisplay( long long int aValue,
 }
 
 double PCB_ORIGIN_TRANSFORMS::ToDisplay( double        aValue,
-                                         COORD_TYPES_T aCoordType )
+                                         COORD_TYPES_T aCoordType ) const
 {
     double value = aValue;
 
@@ -75,7 +75,7 @@ double PCB_ORIGIN_TRANSFORMS::ToDisplay( double        aValue,
 }
 
 long long int PCB_ORIGIN_TRANSFORMS::FromDisplay( long long int aValue,
-                                                  COORD_TYPES_T aCoordType )
+                                                  COORD_TYPES_T aCoordType ) const
 {
     long long value = aValue;
 
@@ -93,7 +93,7 @@ long long int PCB_ORIGIN_TRANSFORMS::FromDisplay( long long int aValue,
 }
 
 double PCB_ORIGIN_TRANSFORMS::FromDisplay( double        aValue,
-                                           COORD_TYPES_T aCoordType )
+                                           COORD_TYPES_T aCoordType ) const
 {
     double value = aValue;
 
diff --git a/pcbnew/pcb_origin_transforms.h b/pcbnew/pcb_origin_transforms.h
index 6657b73252..49e3e2af19 100644
--- a/pcbnew/pcb_origin_transforms.h
+++ b/pcbnew/pcb_origin_transforms.h
@@ -23,7 +23,7 @@
  */
 
 #ifndef PCB_ORIGIN_TRANSFORM_H_
-#define PCB_ORIGIN_TRANSFORM_H_ 1
+#define PCB_ORIGIN_TRANSFORM_H_
 
 #include <origin_transforms.h>
 
@@ -38,16 +38,16 @@ public:
 
     using ORIGIN_TRANSFORMS::ToDisplay;
 
-    virtual long long int ToDisplay( long long int aValue, COORD_TYPES_T aCoordType ) override;
+    virtual long long int ToDisplay( long long int aValue, COORD_TYPES_T aCoordType ) const override;
 
-    virtual double ToDisplay( double aValue, COORD_TYPES_T aCoordType ) override;
+    virtual double ToDisplay( double aValue, COORD_TYPES_T aCoordType ) const override;
 
 
     using ORIGIN_TRANSFORMS::FromDisplay;
 
-    virtual long long int FromDisplay( long long int aValue, COORD_TYPES_T aCoordType ) override;
+    virtual long long int FromDisplay( long long int aValue, COORD_TYPES_T aCoordType ) const override;
 
-    virtual double FromDisplay( double aValue, COORD_TYPES_T aCoordType ) override;
+    virtual double FromDisplay( double aValue, COORD_TYPES_T aCoordType ) const override;
 
 
     /**
diff --git a/pcbnew/pcb_view.cpp b/pcbnew/pcb_view.cpp
index dcf04f16b5..d2cbef7f43 100644
--- a/pcbnew/pcb_view.cpp
+++ b/pcbnew/pcb_view.cpp
@@ -90,13 +90,13 @@ void PCB_VIEW::Remove( KIGFX::VIEW_ITEM* aItem )
 }
 
 
-void PCB_VIEW::Update( KIGFX::VIEW_ITEM* aItem, int aUpdateFlags )
+void PCB_VIEW::Update( const KIGFX::VIEW_ITEM* aItem, int aUpdateFlags ) const
 {
-    BOARD_ITEM* item = static_cast<BOARD_ITEM*>( aItem );
+    const BOARD_ITEM* item = static_cast<const BOARD_ITEM*>( aItem );
 
     if( item->Type() == PCB_MODULE_T )
     {
-        MODULE* mod = static_cast<MODULE*>( item );
+        const MODULE* mod = static_cast<const MODULE*>( item );
 
         mod->RunOnChildren( [this, aUpdateFlags] ( BOARD_ITEM* aModItem )
                             {
@@ -108,7 +108,7 @@ void PCB_VIEW::Update( KIGFX::VIEW_ITEM* aItem, int aUpdateFlags )
 }
 
 
-void PCB_VIEW::Update( KIGFX::VIEW_ITEM* aItem )
+void PCB_VIEW::Update( const KIGFX::VIEW_ITEM* aItem ) const
 {
     PCB_VIEW::Update( aItem, KIGFX::ALL );
 }
diff --git a/pcbnew/pcb_view.h b/pcbnew/pcb_view.h
index eedffb0ac3..2086e8f628 100644
--- a/pcbnew/pcb_view.h
+++ b/pcbnew/pcb_view.h
@@ -46,10 +46,10 @@ public:
     virtual void Remove( VIEW_ITEM* aItem ) override;
 
     /// @copydoc VIEW::Update()
-    virtual void Update( VIEW_ITEM* aItem, int aUpdateFlags ) override;
+    virtual void Update( const VIEW_ITEM* aItem, int aUpdateFlags ) const override;
 
     /// @copydoc VIEW::Update()
-    virtual void Update( VIEW_ITEM* aItem ) override;
+    virtual void Update( const VIEW_ITEM* aItem ) const override;
 
     void UpdateDisplayOptions( const PCB_DISPLAY_OPTIONS& aOptions );
 };
diff --git a/pcbnew/router/pns_index.h b/pcbnew/router/pns_index.h
index f87caa9ad8..56ee6f5fb9 100644
--- a/pcbnew/router/pns_index.h
+++ b/pcbnew/router/pns_index.h
@@ -78,7 +78,7 @@ public:
      * @return number of items found.
      */
     template<class Visitor>
-    int Query( const ITEM* aItem, int aMinDistance, Visitor& aVisitor );
+    int Query( const ITEM* aItem, int aMinDistance, Visitor& aVisitor ) const;
 
     /**
      * Searches items in the index that are in proximity of aShape.
@@ -92,7 +92,7 @@ public:
      * @return number of items found.
      */
     template<class Visitor>
-    int Query( const SHAPE* aShape, int aMinDistance, Visitor& aVisitor );
+    int Query( const SHAPE* aShape, int aMinDistance, Visitor& aVisitor ) const;
 
     /**
      * Returns list of all items in a given net.
@@ -120,7 +120,7 @@ public:
 private:
 
     template <class Visitor>
-    int querySingle( std::size_t aIndex, const SHAPE* aShape, int aMinDistance, Visitor& aVisitor );
+    int querySingle( std::size_t aIndex, const SHAPE* aShape, int aMinDistance, Visitor& aVisitor ) const;
 
     std::deque<ITEM_SHAPE_INDEX> m_subIndices;
     std::map<int, NET_ITEMS_LIST> m_netMap;
@@ -129,16 +129,16 @@ private:
 
 
 template<class Visitor>
-int INDEX::querySingle( std::size_t aIndex, const SHAPE* aShape, int aMinDistance, Visitor& aVisitor )
+int INDEX::querySingle( std::size_t aIndex, const SHAPE* aShape, int aMinDistance, Visitor& aVisitor ) const
 {
     if( aIndex >= m_subIndices.size() )
         return 0;
 
-    return m_subIndices[aIndex].Query( aShape, aMinDistance, aVisitor, false );
+    return m_subIndices[aIndex].Query( aShape, aMinDistance, aVisitor);
 }
 
 template<class Visitor>
-int INDEX::Query( const ITEM* aItem, int aMinDistance, Visitor& aVisitor )
+int INDEX::Query( const ITEM* aItem, int aMinDistance, Visitor& aVisitor ) const
 {
     int total = 0;
 
@@ -151,7 +151,7 @@ int INDEX::Query( const ITEM* aItem, int aMinDistance, Visitor& aVisitor )
 }
 
 template<class Visitor>
-int INDEX::Query( const SHAPE* aShape, int aMinDistance, Visitor& aVisitor )
+int INDEX::Query( const SHAPE* aShape, int aMinDistance, Visitor& aVisitor ) const
 {
     int total = 0;
 
diff --git a/pcbnew/tools/selection_tool.h b/pcbnew/tools/selection_tool.h
index 23dbabf7be..297b7c4306 100644
--- a/pcbnew/tools/selection_tool.h
+++ b/pcbnew/tools/selection_tool.h
@@ -179,7 +179,7 @@ public:
     ///> Zooms the screen to center and fit the current selection.
     void zoomFitSelection();
 
-    BOARD* GetBoard()
+    BOARD* GetBoard() const
     {
         return board();
     }
@@ -394,4 +394,4 @@ private:
     std::unique_ptr<PRIV> m_priv;
 };
 
-#endif
+#endif /* __SELECTION_TOOL_H */
diff --git a/pcbnew/widgets/appearance_controls.cpp b/pcbnew/widgets/appearance_controls.cpp
index ece962c951..231fcc4dc6 100644
--- a/pcbnew/widgets/appearance_controls.cpp
+++ b/pcbnew/widgets/appearance_controls.cpp
@@ -208,18 +208,18 @@ NET_GRID_ENTRY& NET_GRID_TABLE::GetEntry( int aRow )
 }
 
 
-int NET_GRID_TABLE::GetRowByNetcode( int aCode )
+int NET_GRID_TABLE::GetRowByNetcode( int aCode ) const
 {
-    auto it = std::find_if( m_nets.begin(), m_nets.end(),
+    auto it = std::find_if( m_nets.cbegin(), m_nets.cend(),
             [aCode]( const NET_GRID_ENTRY& aEntry )
             {
                 return aEntry.code == aCode;
             } );
 
-    if( it == m_nets.end() )
+    if( it == m_nets.cend() )
         return -1;
 
-    return std::distance( m_nets.begin(), it );
+    return std::distance( m_nets.cbegin(), it );
 }
 
 
diff --git a/pcbnew/widgets/appearance_controls.h b/pcbnew/widgets/appearance_controls.h
index e017326fc8..05e1135718 100644
--- a/pcbnew/widgets/appearance_controls.h
+++ b/pcbnew/widgets/appearance_controls.h
@@ -112,7 +112,7 @@ public:
 
     NET_GRID_ENTRY& GetEntry( int aRow );
 
-    int GetRowByNetcode( int aCode );
+    int GetRowByNetcode( int aCode ) const;
 
     void Rebuild();