diff --git a/EGkGdbIterator.h b/EGkGdbIterator.h
index 37d5749..fcfe8d2 100644
--- a/EGkGdbIterator.h
+++ b/EGkGdbIterator.h
@@ -37,7 +37,8 @@ class __declspec( novtable) IGdbIterator
 
       virtual GdbType  GetGdbType( void) const = 0 ;
       virtual IGeoObj* GetGeoObj( void) = 0 ;
-      virtual Frame3d* GetGroupFrame( void) = 0 ;
+      virtual IGeoFrame3d* GetGeoFrame( void) = 0 ;
+      virtual bool GetGroupFrame( Frame3d& frGlob) = 0 ;
       virtual bool GetGroupGlobFrame( Frame3d& frGlob) = 0 ;
       virtual int  GetId( void) = 0 ;
       virtual int  GetParentId( void) = 0 ;
diff --git a/EGkGeoObj.h b/EGkGeoObj.h
index a2da912..f3fe759 100644
--- a/EGkGeoObj.h
+++ b/EGkGeoObj.h
@@ -49,8 +49,9 @@ class __declspec( novtable) IGeoObj
       virtual bool Mirror( const Point3d& ptOn, const Vector3d& vtNorm) = 0 ;
       virtual bool ToGlob( const Frame3d& frRef) = 0 ;
       virtual bool ToLoc( const Frame3d& frRef) = 0 ;
-      virtual void SetObjGraphics( IObjGraphics* pOGr) ;
-      virtual IObjGraphics* GetObjGraphics( void) ;
+      virtual void SetObjGraphics( IObjGraphics* pOGr) = 0 ;
+      virtual IObjGraphics* GetObjGraphics( void) = 0 ;
+      virtual const IObjGraphics* GetObjGraphics( void) const = 0 ;
 } ;
 
 //-----------------------------------------------------------------------------
diff --git a/EGkPolyLine.h b/EGkPolyLine.h
index 7e97508..4bfe7df 100644
--- a/EGkPolyLine.h
+++ b/EGkPolyLine.h
@@ -1,7 +1,7 @@
 //----------------------------------------------------------------------------
 //  EgalTech 2013-2013
 //----------------------------------------------------------------------------
-// File : EGkPolyLine.cpp       Data : 22.12.13          Versione : 1.4l3
+// File : EGkPolyLine.h         Data : 22.12.13          Versione : 1.4l3
 // Contenuto : Dichiarazione della classe PolyLine.
 //
 //
diff --git a/EgkObjGraphics.h b/EgkObjGraphics.h
index f079d90..b33ea36 100644
--- a/EgkObjGraphics.h
+++ b/EgkObjGraphics.h
@@ -18,6 +18,6 @@
 class __declspec( novtable) IObjGraphics
 {
    public :
-      ~IObjGraphics( void) {}
+      virtual ~IObjGraphics( void) {}
       virtual void Invalidate( void) = 0 ;
 } ;