diff --git a/EgtGeomKernel.rc b/EgtGeomKernel.rc
index 0bf55eb..3b3448e 100644
Binary files a/EgtGeomKernel.rc and b/EgtGeomKernel.rc differ
diff --git a/PolyArc.cpp b/PolyArc.cpp
index 17cee6c..30a0e5b 100644
--- a/PolyArc.cpp
+++ b/PolyArc.cpp
@@ -479,10 +479,10 @@ PolyArc::Invert( bool bInvertU)
       return true ;
   // inverto la lista
    m_lUPointBs.reverse() ;
-  // sposto il bulge all'estremo iniziale di ogni tratto (l'ultimo non conta)
+  // sposto il bulge all'estremo iniziale di ogni tratto (l'ultimo non conta) e lo inverto
    for ( UPNTBLIST::iterator iter = m_lUPointBs.begin() ; iter != m_lUPointBs.end() ; ++ iter) {
       if ( next( iter) != m_lUPointBs.end())
-         iter->dB = next( iter)->dB ;
+         iter->dB = - next( iter)->dB ;
       else
          iter->dB = 0 ;
    }
diff --git a/SfrCreate.cpp b/SfrCreate.cpp
index b71e176..de8a92c 100644
--- a/SfrCreate.cpp
+++ b/SfrCreate.cpp
@@ -43,7 +43,7 @@ GetSurfFlatRegionRectangle( double dWidth, double dLen)
    if ( IsNull( pCC)  ||  ! pCC->FromPolyLine( PL))
       return nullptr ;
   // creo il rettangolo
-   PtrOwner<ISurfFlatRegion> pSfr( CreateSurfFlatRegion()) ;
+   PtrOwner<SurfFlatRegion> pSfr( CreateBasicSurfFlatRegion()) ;
    if ( IsNull( pSfr)  ||  ! pSfr->AddExtLoop( Release( pCC)))
       return nullptr ;
    else
@@ -82,7 +82,7 @@ GetSurfFlatRegionStadium( double dWidth, double dLen)
    if ( IsNull( pCC)  ||  ! pCC->FromPolyArc( PA))
       return nullptr ;
   // creo il rettangolo
-   PtrOwner<ISurfFlatRegion> pSfr( CreateSurfFlatRegion()) ;
+   PtrOwner<SurfFlatRegion> pSfr( CreateBasicSurfFlatRegion()) ;
    if ( IsNull( pSfr)  ||  ! pSfr->AddExtLoop( Release( pCC)))
       return nullptr ;
    else
@@ -102,7 +102,7 @@ GetSurfFlatRegionDisk( double dRadius)
       return nullptr ;
    pArc->Set( ORIG, Z_AX, dRadius, X_AX, ANG_FULL, 0) ;
   // creo il disco
-   PtrOwner<ISurfFlatRegion> pSfr( CreateSurfFlatRegion()) ;
+   PtrOwner<SurfFlatRegion> pSfr( CreateBasicSurfFlatRegion()) ;
    if ( IsNull( pSfr)  ||  ! pSfr->AddExtLoop( Release( pArc)))
       return nullptr ;
    else