Properly update toolbar buttons on application start

gerbview/events_called_functions.cpp

@@ -162,6 +162,8 @@ BEGIN_EVENT_TABLE( GERBVIEW_FRAME, EDA_DRAW_FRAME )
     EVT_UPDATE_UI( ID_TB_OPTIONS_SHOW_NEGATIVE_ITEMS, GERBVIEW_FRAME::OnUpdateShowNegativeItems )
     EVT_UPDATE_UI( ID_TB_OPTIONS_SHOW_LAYERS_MANAGER_VERTICAL_TOOLBAR,
                    GERBVIEW_FRAME::OnUpdateShowLayerManager )
+    EVT_UPDATE_UI( ID_TB_OPTIONS_DIFF_MODE, GERBVIEW_FRAME::OnUpdateDiffMode )
+    EVT_UPDATE_UI( ID_TB_OPTIONS_HIGH_CONTRAST_MODE, GERBVIEW_FRAME::OnUpdateHighContrastMode )
 
     EVT_UPDATE_UI( ID_TOOLBARH_GERBER_SELECT_ACTIVE_DCODE, GERBVIEW_FRAME::OnUpdateSelectDCode )
     EVT_UPDATE_UI( ID_TOOLBARH_GERBVIEW_SELECT_ACTIVE_LAYER,

gerbview/gerbview_frame.h

@@ -563,6 +563,8 @@ public:
     void                OnUpdateShowLayerManager( wxUpdateUIEvent& aEvent );
     void                OnUpdateSelectDCode( wxUpdateUIEvent& aEvent );
     void                OnUpdateLayerSelectBox( wxUpdateUIEvent& aEvent );
+    void                OnUpdateDiffMode( wxUpdateUIEvent& aEvent );
+    void                OnUpdateHighContrastMode( wxUpdateUIEvent& aEvent );
 
     /**
      * Function BlockCommand

gerbview/toolbars_gerber.cpp

@@ -541,6 +541,18 @@ void GERBVIEW_FRAME::OnUpdateShowNegativeItems( wxUpdateUIEvent& aEvent )
 }
 
 
+void GERBVIEW_FRAME::OnUpdateDiffMode( wxUpdateUIEvent& aEvent )
+{
+    aEvent.Check( m_DisplayOptions.m_DiffMode );
+}
+
+
+void GERBVIEW_FRAME::OnUpdateHighContrastMode( wxUpdateUIEvent& aEvent )
+{
+    aEvent.Check( m_DisplayOptions.m_HighContrastMode );
+}
+
+
 void GERBVIEW_FRAME::OnUpdateShowLayerManager( wxUpdateUIEvent& aEvent )
 {
     aEvent.Check( m_show_layer_manager_tools );