diff --git a/EgtGraphics.rc b/EgtGraphics.rc
index 619d357..b4afa94 100644
Binary files a/EgtGraphics.rc and b/EgtGraphics.rc differ
diff --git a/SceneBasic.cpp b/SceneBasic.cpp
index 8b97ac9..1843fbd 100644
--- a/SceneBasic.cpp
+++ b/SceneBasic.cpp
@@ -437,8 +437,8 @@ Scene::CalcDimViewFromExtView( void)
 
   // ricavo le dimensioni
    const double COEFF = 1.05 ;
-   double dHalfWidth = COEFF * max( fabs( ptMin.x), fabs( ptMax.x)) ;
-   double dHalfHeight = COEFF * max( fabs( ptMin.y), fabs( ptMax.y)) ;
+   double dHalfWidth = COEFF * max( abs( ptMin.x), abs( ptMax.x)) ;
+   double dHalfHeight = COEFF * max( abs( ptMin.y), abs( ptMax.y)) ;
 
   // adatto le dimensioni a quelle della vista
    return AdjustDimView( dHalfWidth, dHalfHeight) ;
diff --git a/SceneCamera.cpp b/SceneCamera.cpp
index 90bd36c..bd8d545 100644
--- a/SceneCamera.cpp
+++ b/SceneCamera.cpp
@@ -133,13 +133,13 @@ Scene::GetCamera( double* pdAngVertDeg, double* pdAngOrizzDeg, double* pdDist) c
    double dAngVertDeg ;
    double dAngOrizzDeg ;
    m_vtDirCamera.ToSpherical( nullptr, &dAngVertDeg, &dAngOrizzDeg) ;
-   if ( fabs( dAngVertDeg) < EPS_ANG_SMALL) {
+   if ( abs( dAngVertDeg) < EPS_ANG_SMALL) {
       if ( m_bUpOk)
          (-m_vtUp).ToSpherical( nullptr, nullptr, &dAngOrizzDeg) ;
       else
          dAngOrizzDeg = -90 ;
    }
-   else if ( fabs( dAngVertDeg - ANG_STRAIGHT) < EPS_ANG_SMALL) {
+   else if ( abs( dAngVertDeg - ANG_STRAIGHT) < EPS_ANG_SMALL) {
       if ( m_bUpOk)
          (m_vtUp).ToSpherical( nullptr, nullptr, &dAngOrizzDeg) ;
       else
@@ -392,8 +392,8 @@ Scene::ZoomWin( const Point3d& ptWin1, const Point3d& ptWin2)
    SetCenter( ptNewCen) ;
 
   // imposto il nuovo zoom
-   double dHalfWidth = 0.5 * fabs( ptView1.x - ptView2.x) ;
-   double dHalfHeight = 0.5 * fabs( ptView1.y - ptView2.y) ;
+   double dHalfWidth = 0.5 * abs( ptView1.x - ptView2.x) ;
+   double dHalfHeight = 0.5 * abs( ptView1.y - ptView2.y) ;
 
   // adatto le dimensioni a quelle della vista
    return AdjustDimView( dHalfWidth, dHalfHeight) ;
diff --git a/SceneGeom.cpp b/SceneGeom.cpp
index af9c251..243ccc6 100644
--- a/SceneGeom.cpp
+++ b/SceneGeom.cpp
@@ -281,7 +281,7 @@ Scene::DrawGeoObj( const IGdbIterator& iIter, int nPass, const MdStMkCol& siObj)
          double dTh ;
          Vector3d vtExtr ;
          if ( pCurve->GetExtrusion( vtExtr)  &&  ! vtExtr.IsSmall()  &&
-              pCurve->GetThickness( dTh)  &&  fabs( dTh) > EPS_SMALL) {
+              pCurve->GetThickness( dTh)  &&  abs( dTh) > EPS_SMALL) {
            // segmenti di raccordo
             PNTVECTOR vPnt ;
             bool bDense = ( nGeoType == CRV_ARC  ||  nGeoType == CRV_BEZ) ;
diff --git a/SceneGrid.cpp b/SceneGrid.cpp
index 4d89e34..a3c2cbf 100644
--- a/SceneGrid.cpp
+++ b/SceneGrid.cpp
@@ -33,7 +33,7 @@ bool
 Scene::SetGridGeo( double dSnapStep, int nMinLineSstep, int nMajLineSstep, int nExtSstep)
 {
    const double MIN_SNAP_STEP = 0.1 ;
-   m_dSnapStep = std::max( fabs( dSnapStep), MIN_SNAP_STEP) ;
+   m_dSnapStep = max( abs( dSnapStep), MIN_SNAP_STEP) ;
    m_nMinLineSstep = abs( nMinLineSstep) ;
    m_nMajLineSstep = abs( nMajLineSstep) ;
    m_nExtSstep = abs( nExtSstep) ;
@@ -127,6 +127,10 @@ Scene::DrawGrid( void)
       glColor3f( LIME.GetRed(), LIME.GetGreen(), LIME.GetBlue()) ;
       glVertex3f( 0, 0, Z_DOWN) ;
       glVertex3f( 0, dExt, Z_DOWN) ;
+      // asse Z+
+      glColor3f( BLUE.GetRed(), BLUE.GetGreen(), BLUE.GetBlue()) ;
+      glVertex3f( 0, 0, Z_DOWN) ;
+      glVertex3f( 0, 0, float( m_nMajLineSstep * m_dSnapStep)) ;
       // se richiesta griglia, assi X- e Y-
       if ( m_bShowGrid) {
          glColor3f( m_colMajLine.GetRed(), m_colMajLine.GetGreen(), m_colMajLine.GetBlue()) ;
diff --git a/SceneSelect.cpp b/SceneSelect.cpp
index 2837c08..d476d85 100644
--- a/SceneSelect.cpp
+++ b/SceneSelect.cpp
@@ -319,7 +319,7 @@ Scene::GetPointFromSelect( int nSelId, const Point3d& ptView, Point3d& ptSel, in
       double dTh ;
       Vector3d vtExtr ;
       if ( pCrv->GetExtrusion( vtExtr)  &&  ! vtExtr.IsSmall()  &&
-           pCrv->GetThickness( dTh)  &&  fabs( dTh) > EPS_SMALL) {
+           pCrv->GetThickness( dTh)  &&  abs( dTh) > EPS_SMALL) {
          vtExtr *= dTh ;
          vtExtr.ToGlob( frEnt) ;
         // correggo il punto di riferimento del contrario dell'estrusione
diff --git a/SceneSnap.cpp b/SceneSnap.cpp
index f12aa7b..f71a72a 100644
--- a/SceneSnap.cpp
+++ b/SceneSnap.cpp
@@ -90,7 +90,7 @@ Scene::GetGridSnapPointZ( bool bSketch, const Point3d& ptWin, const Point3d& ptG
 
   // determino l'intersezione della linea di mira con il piano di elevazione
    double dDenom = vtLine * vtNorm ;
-   if ( fabs( dDenom) < COS_ORTO_ANG_SMALL)
+   if ( abs( dDenom) < COS_ORTO_ANG_SMALL)
       return false ;
    double dU = ( ( ptGrid - ptLine) * vtNorm) / dDenom ;
    Point3d ptNear = ptLine + dU * vtLine ;
@@ -119,7 +119,7 @@ Scene::FindGridSnapPoint( bool bSketch, const Point3d& ptWin)
 
   // determino l'intersezione di questa linea con il piano della griglia
    double dDenom = vtLine * frGrid.VersZ() ;
-   if ( fabs( dDenom) < COS_ORTO_ANG_SMALL)
+   if ( abs( dDenom) < COS_ORTO_ANG_SMALL)
       return false ;
    double dU = ( ( frGrid.Orig() - ptLine) * frGrid.VersZ()) / dDenom ;
    m_ptLastSnapPnt = ptLine + dU * vtLine ;
@@ -499,7 +499,7 @@ Scene::AdjustForCurveExtr( const Point3d& ptWin, const Frame3d& frEnt, const ICu
    double dTh ;
    Vector3d vtExtr ;
    if ( ! pCrv->GetExtrusion( vtExtr)  ||  vtExtr.IsSmall()  ||
-        ! pCrv->GetThickness( dTh)  ||  fabs( dTh) < EPS_SMALL)
+        ! pCrv->GetThickness( dTh)  ||  abs( dTh) < EPS_SMALL)
       return false ;
    vtExtr *= dTh ;
 
@@ -1005,7 +1005,7 @@ Scene::GetPlaneSnapPoint( const Point3d& ptWin, const Plane3d& plPlane, Point3d&
 
   // determino l'intersezione di questa linea con il piano
    double dDenom = vtLine * plPlane.GetVersN() ;
-   if ( fabs( dDenom) < COS_ORTO_ANG_ZERO)
+   if ( abs( dDenom) < COS_ORTO_ANG_ZERO)
       return false ;
    double dU = ( plPlane.GetDist() - ( ptLine - ORIG) * plPlane.GetVersN()) / dDenom ;
    ptSel = ptLine + dU * vtLine ;