diff --git a/Controller.vb b/Controller.vb
index 239b29d..8b06173 100644
--- a/Controller.vb
+++ b/Controller.vb
@@ -1636,9 +1636,7 @@ Public Class Controller
       Select Case EgtGetType(nId)
       Case GDB_TY.GEO_POINT
          Dim ptOrig As Point3d
-         If Not EgtStartPoint(nId, GDB_ID.ROOT, ptOrig) Then
-            Return False
-         End If
+         If Not EgtStartPoint(nId, GDB_ID.ROOT, ptOrig) Then Return False
          Dim frNew As Frame3d = EgtGetGridFrame()
          frNew.ChangeOrigin(ptOrig)
          EnableCommandLog()
@@ -1646,31 +1644,17 @@ Public Class Controller
          DisableCommandLog()
       Case GDB_TY.GEO_FRAME
          Dim frNew As New Frame3d
-         If Not EgtFrame(nId, GDB_ID.ROOT, frNew) Then
-            Return False
-         End If
+         If Not EgtFrame(nId, GDB_ID.ROOT, frNew) Then Return False
          EnableCommandLog()
          EgtSetGridFrame(frNew)
          DisableCommandLog()
-      Case GDB_TY.CRV_ARC
+      Case GDB_TY.CRV_LINE, GDB_TY.CRV_ARC, GDB_TY.CRV_BEZ, GDB_TY.CRV_COMPO
          Dim vtZ As Vector3d
          If Not EgtCurveExtrusion(nId, vtZ) OrElse vtZ.IsSmall() Then
-            EgtArcNormVersor(nId, vtZ)
+            If Not EgtArcNormVersor(nId, vtZ) Then vtZ = Vector3d.Z_AX
          End If
          Dim ptOrig As Point3d
-         EgtMidPoint(nId, ptOrig)
-         Dim frNew As New Frame3d
-         frNew.Setup(ptOrig.Glob(nId), vtZ.Glob(nId))
-         EnableCommandLog()
-         EgtSetGridFrame(frNew)
-         DisableCommandLog()
-      Case GDB_TY.CRV_LINE, GDB_TY.CRV_BEZ, GDB_TY.CRV_COMPO
-         Dim vtZ As Vector3d
-         If Not EgtCurveExtrusion(nId, vtZ) OrElse vtZ.IsSmall() Then
-            vtZ = Vector3d.Z_AX
-         End If
-         Dim ptOrig As Point3d
-         EgtMidPoint(nId, ptOrig)
+         EgtCentroid(nId, ptOrig)
          Dim frNew As New Frame3d
          frNew.Setup(ptOrig.Glob(nId), vtZ.Glob(nId))
          EnableCommandLog()
@@ -5115,7 +5099,13 @@ Public Class Controller
          Dim nCount As Integer
          EgtOffsetCurveAdv(nId, m_dLast, m_nLast, nCount)
          If nCount <= 0 Then
+            Dim vtPlaN As Vector3d
+            Dim dPlaDist As Double
+            If EgtCurveIsFlat(nId, vtPlaN, dPlaDist) Then
             RaiseEvent OutputInfo(Me, EgtMsg(2056))        ' Distance too big
+            Else
+               RaiseEvent OutputInfo(Me, EgtMsg(2057))        ' Curve not flat (in its plane)
+            End If
          Else
             EgtErase(nId)
             RaiseEvent OutputInfo(Me, "")
@@ -5138,6 +5128,11 @@ Public Class Controller
             Dim dDistFr As Double = vtDiff.Len()
             ' assegno la distanza di offset tenendo conto del lato ( sx=-1, dx=+1) 
             m_dLast = dDistFr * nSide
+            ' se vettore estrusione della curva opposto al versore Z della griglia, devo cambiare segno alla distanza
+            Dim vtExtr As Vector3d
+            If EgtCurveExtrusion(nId, vtExtr) And Not vtExtr.IsSmall() Then
+               If vtExtr * EgtGetGridVersZ() < -EPS_SMALL Then m_dLast = -m_dLast
+            End If
          End If
       End If
       Return False
diff --git a/My Project/AssemblyInfo.vb b/My Project/AssemblyInfo.vb
index f55cd77..fb317f5 100644
--- a/My Project/AssemblyInfo.vb	
+++ b/My Project/AssemblyInfo.vb	
@@ -46,5 +46,5 @@ Imports System.Runtime.InteropServices
 ' utilizzando l'asterisco (*) come descritto di seguito:
 ' <Assembly: AssemblyVersion("1.0.*")> 
 
-<Assembly: AssemblyVersion("1.9.8.2")> 
-<Assembly: AssemblyFileVersion("1.9.8.2")> 
+<Assembly: AssemblyVersion("1.9.8.4")> 
+<Assembly: AssemblyFileVersion("1.9.8.4")>