diff --git a/MyVeinMatch/VeinMatchingWindow.xaml.vb b/MyVeinMatch/VeinMatchingWindow.xaml.vb
index 06d9732..6f1f299 100644
--- a/MyVeinMatch/VeinMatchingWindow.xaml.vb
+++ b/MyVeinMatch/VeinMatchingWindow.xaml.vb
@@ -313,25 +313,36 @@ Public Class VeinMatchingWindow
                PartSolidIdTempSel.nIdLineFirst = nId
                EgtSetMark(nId)
                Return
-            ElseIf EgtGetType(nId) = GDB_TY.CRV_LINE And PartSolidIdTempSel.nIdLineSecond = -1 Then
+               ' impongo anche che il secondo lato appartenga ad un solid diverso dal primo selezionato
+            ElseIf EgtGetType(nId) = GDB_TY.CRV_LINE And PartSolidIdTempSel.nIdLineSecond = -1 And
+               nPartId <> PartSolidIdTempSel.PartId And nPartId <> PartSolidIdTempSel.PartSolidId Then
                PartSolidIdTempSel.nIdLineSecond = nId
                EgtSetMark(nId)
                PairPart(False)
                Return
-            ElseIf EgtGetType(nId) = GDB_TY.CRV_LINE And PartSolidIdTempSel.nIdLineSecond <> -1 Then
+               ' impongo anche che il secondo lato appartenga ad un solid diverso dal primo selezionato
+            ElseIf EgtGetType(nId) = GDB_TY.CRV_LINE And PartSolidIdTempSel.nIdLineSecond <> -1 And
+               nPartId <> PartSolidIdTempSel.PartId And nPartId <> PartSolidIdTempSel.PartSolidId Then
                EgtResetMark(PartSolidIdTempSel.nIdLineSecond)
                EgtSetMark(nId)
                PartSolidIdTempSel.nIdLineSecond = nId
                PairPart(False)
                Return
+               ' impongo che la prima faccia appartenga al primo solido selezionato
             ElseIf (ModifierKeys.Shift And Keyboard.Modifiers) > 0 And EgtGetType(nId) = GDB_TY.SRF_FRGN And
-               PartSolidIdTempSel.nIdLineSecond <> -1 And PartSolidIdTempSel.nIdSurfFirst = -1 Then
+               PartSolidIdTempSel.nIdLineSecond <> -1 And PartSolidIdTempSel.nIdSurfFirst = -1 And
+               nPartId = PartSolidIdTempSel.PartSolidId Then
                PartSolidIdTempSel.nIdSurfFirst = nId
                EgtSurfFrNormVersor(nId, GDB_ID.ROOT, PartSolidIdTempSel.vtNormFirst)
                EgtSetMark(nId)
                Return
+               ' impongo che la seconda faccia appartenga ad un solido diverso dal primo selezionato
             ElseIf (ModifierKeys.Shift And Keyboard.Modifiers) > 0 And EgtGetType(nId) = GDB_TY.SRF_FRGN And
                PartSolidIdTempSel.nIdLineSecond <> -1 And PartSolidIdTempSel.nIdSurfFirst <> -1 Then
+               If nPartId = PartSolidIdTempSel.PartSolidId Then
+                  MyMsgTxBl.Text = "Devi selezionare una faccia appartente ad un altro pezzo"
+                  Return
+               End If
                EgtSurfFrNormVersor(nId, GDB_ID.ROOT, PartSolidIdTempSel.vtNormSecond)
                EgtResetMark(PartSolidIdTempSel.nIdSurfSecond)
                PartSolidIdTempSel.nIdSurfSecond = nId
@@ -344,7 +355,6 @@ Public Class VeinMatchingWindow
             Continue While
          End If
 
-         'Dim PartSolidIdSel As PartSolid = GetPartSolid(nPartId)
          ' selezione semplice
          If EgtIsPart(nPartId) Then
             Dim nStat As Integer = GDB_ST.ON_
@@ -618,11 +628,14 @@ Public Class VeinMatchingWindow
          If m_nIdToSel <> GDB_ID.NULL Then
             ' Eseguo la selezione in Nesting
             Dim PartSolidIdToSel As PartSolid = GetPartSolid(m_nIdToSel)
-            If IsNothing(PartSolidIdToSel) Then
-               ' selezione di un Part che non ha un SOLID associato
-               EgtSelectObj(m_nIdToSel)
-               Return
-            End If
+
+            ' in teoria questo controllo non serve, perché creo un part Solid per tutti i part e se non hanno il solid non è un problema
+            'If IsNothing(PartSolidIdToSel) Then
+            '   'selezione di un Part che non ha un SOLID associato
+            '   EgtSelectObj(m_nIdToSel)
+            '   Return
+            'End If
+
             m_nIdToSel = PartSolidIdToSel.PartId
             ' seleziono
             Dim bSelected As Boolean = False
@@ -990,14 +1003,11 @@ Public Class VeinMatchingWindow
       'TgBtn4.IsChecked = False
       Text5.Text = "0"
       m_dAngRot = 0
+      If m_nIdPart = GDB_ID.NULL Then Return
       Dim PartSolidSel = GetPartSolid(m_nIdPart)
-      If Not IsNothing(PartSolidSel) Then
-         'PartSolidSel.ConfirmRotate()
-         PartSolidSel.DeselectPart()
-         PartSolidSel.ResetData()
-      Else
-         EgtDeselectAll()
-      End If
+      'PartSolidSel.ConfirmRotate()
+      PartSolidSel.DeselectPart()
+      PartSolidSel.ResetData()
       m_nIdPart = -1
       EgtDraw()
    End Sub
@@ -1070,6 +1080,7 @@ Public Class VeinMatchingWindow
             ptIni = ptEndF
             ptFin = ptEndS
          Case 4
+            ' Mid-Mid
             ptIni = ptMidF
             ptFin = ptMidS
          Case Else
@@ -1086,7 +1097,7 @@ Public Class VeinMatchingWindow
          'PartSolidIdSel.nIdLineSecond = -1
 
          'If FindInters(PartSolidIdSel.PartId) Then
-         '   MyMsgTxBl.Text = "Ciula!"
+         '   MyMsgTxBl.Text = MyMsgTxBl.Text & "Ciula!"
          '   MyMsgTxBl.Foreground = Brushes.Red
          'End If
          EgtDraw()
@@ -1096,13 +1107,14 @@ Public Class VeinMatchingWindow
       Dim vtAx As Vector3d = vtDirF ^ vtDirS
       PartSolidIdSel.Rotate(ptFin, vtAx, dAng, bPart)
       'If FindInters(PartSolidIdSel.PartId) Then
-      '   MyMsgTxBl.Text = "Ciula!"
+      '   MyMsgTxBl.Text = MyMsgTxBl.Text & "Ciula!"
       '   MyMsgTxBl.Foreground = Brushes.Red
       'End If
       EgtDraw()
    End Sub
 
    Private Sub TgBtn6_Uncheck() Handles TgBtn6.Unchecked
+      If m_nIdPart = GDB_ID.NULL Then Return
       ' conferma l'accoppiamento
       Dim PartSolidSel As PartSolid = GetPartSolid(m_nIdPart)
       'PairPart(True)   '' questo servirà per accoppiare il part col suo solid dopo un accoppiamento tra solidi
@@ -1111,17 +1123,28 @@ Public Class VeinMatchingWindow
       PartSolidSel.DeselectPart()
       m_nIdPart = -1
       'TgBtn6.IsChecked = False
+      MyMsgTxBl.Text = "ciao mondo ciao mondo ciao mondo ciao mondo ciao mona ciao mondo ciao mondo"
       EgtDraw()
    End Sub
 
    Private Sub PairOption_Changed() Handles PairOption.SelectionChanged
       If Not TgBtn6.IsChecked Then Return
+      If m_nIdPart = GDB_ID.NULL Then Return
       PairPart(False)
+      'If FindInters(m_nIdPart) Then
+      '   MyMsgTxBl.Text = MyMsgTxBl.Text & "Ciula!"
+      '   MyMsgTxBl.Foreground = Brushes.Red
+      'End If
    End Sub
 
    Private Sub InvertOption_Changed() Handles InvertOption.Click
       If Not TgBtn6.IsChecked Then Return
+      If m_nIdPart = GDB_ID.NULL Then Return
       PairPart(False)
+      'If FindInters(m_nIdPart) Then
+      '   MyMsgTxBl.Text = MyMsgTxBl.Text & "Ciula!"
+      '   MyMsgTxBl.Foreground = Brushes.Red
+      'End If
    End Sub
 
    Private Sub CompletePair()
@@ -1142,6 +1165,7 @@ Public Class VeinMatchingWindow
    End Sub
 
    Private Sub ResetPair()
+      If m_nIdPart = GDB_ID.NULL Then Return
       Dim PartSolidSel As PartSolid = GetPartSolid(m_nIdPart)
       PartSolidSel.ResetData()
       EgtDraw()
@@ -1160,24 +1184,39 @@ Public Class VeinMatchingWindow
    Private Function FindInters(nPartId As Integer) As Boolean
       Dim PartSolidCurr As PartSolid = GetPartSolid(nPartId)
       Dim nIdTempL = EgtGetFirstNameInGroup(PartSolidCurr.PartSolidId, "Temp")
-      Dim nIdSurf As Integer = PartSolidCurr.SurfId
-      EgtSetCurrentContext(m_nVeinCtx)
-      For Each PartSolidSel As PartSolid In m_PartSolidList
-         Dim nIdSurfToCheck As Integer = PartSolidSel.SurfId
-         If nIdSurfToCheck = -1 Then Continue For
-         Dim nIdCopy As Integer = EgtCopy(nIdSurf, nIdTempL)
-         EgtSurfTmIntersect(nIdCopy, nIdSurf)
-      Next
+      ' svuoto il layer prima di trovare le nuove intersezioni
       Dim nIdInters As Integer = EgtGetFirstInGroup(nIdTempL)
+      While nIdInters <> GDB_ID.NULL
+         Dim nIdNext As Integer = EgtGetNext(nIdInters)
+         EgtErase(nIdInters)
+         nIdInters = nIdNext
+      End While
+      Dim nIdSolid As Integer = PartSolidCurr.SolidId
+      EgtSetCurrentContext(m_nVeinCtx)
+      Dim vIntersId As New ObservableCollection(Of Integer)
+      For Each PartSolidSel As PartSolid In m_PartSolidList
+         Dim nIdSurfToCheck As Integer = PartSolidSel.SolidId
+         If nIdSurfToCheck = -1 Then Continue For
+         Dim nIdCopy As Integer = EgtCopy(nIdSolid, nIdTempL)
+         EgtSurfTmIntersect(nIdCopy, nIdSurfToCheck)
+         If EgtSurfTmFacetCount(nIdCopy) <> 0 Then
+            EgtSetColor(nIdCopy, New Color3d(255, 0, 0))
+            vIntersId.Add(PartSolidSel.PartId)
+         End If
+      Next
+      nIdInters = EgtGetFirstInGroup(nIdTempL)
       ' se trovo delle intersezioni metto tutto in trasparenza tranne le intersezioni
       If nIdInters <> -1 Then
-         For Each PartSolidSel As PartSolid In m_PartSolidList
+         'EgtSetMark(nIdTempL)
+         For Each PartId As Integer In vIntersId
+            Dim PartSolidSel As PartSolid = GetPartSolid(PartId)
             PartSolidSel.MakeTransparent()
          Next
          Return True
       Else
          For Each PartSolidSel As PartSolid In m_PartSolidList
             PartSolidSel.MakeOpaque()
+            MyMsgTxBl.Foreground = Brushes.DarkKhaki
          Next
       End If
       Return False
@@ -1194,6 +1233,7 @@ Public Class VeinMatchingWindow
       End If
       If TgBtn6.IsChecked Then
          TgBtn6.IsChecked = False
+         If m_nIdPart = GDB_ID.NULL Then Return
          Dim PartSolidSel = GetPartSolid(m_nIdPart)
          PartSolidSel.ResetMark()
          PartSolidSel.ResetData()
@@ -1219,13 +1259,17 @@ Public Class VeinMatchingWindow
 
    Private Sub Flip_Changed() Handles FlipOption.Click
       If TgBtn6.IsChecked = False Then Return
+      If m_nIdPart = GDB_ID.NULL Then Return
       Dim PartSolidSel As PartSolid = GetPartSolid(m_nIdPart)
       Dim vtNorm As New Vector3d
       EgtSurfFrNormVersor(PartSolidSel.SurfId, GDB_ID.ROOT, vtNorm)
       Dim ptMid As New Point3d
       EgtMidPoint(PartSolidSel.nIdLineFirst, GDB_ID.ROOT, ptMid)
       PartSolidSel.Rotate(ptMid, vtNorm, 180)
-      'FindInters(m_nIdPart)
+      'If FindInters(m_nIdPart) Then
+      '   MyMsgTxBl.Text = MyMsgTxBl.Text & "Ciula!"
+      '   MyMsgTxBl.Foreground = Brushes.Red
+      'End If
       EgtDraw()
    End Sub