diff --git a/Generator.cpp b/Generator.cpp
index 6293dc7..febf1c8 100644
--- a/Generator.cpp
+++ b/Generator.cpp
@@ -164,7 +164,7 @@ Generator::Run( const string& sCncFile, const std::string& sInfo)
 
   // ciclo su tutte le operazioni della macchinata
    int nInd = 0 ;
-   int nOpId = m_pMchMgr->GetFirstOperation() ;
+   int nOpId = m_pMchMgr->GetFirstActiveOperation() ;
    while ( bOk  &&  nOpId != GDB_ID_NULL) {
      // incremento l'indice della operazione
       ++ nInd ;
@@ -191,7 +191,7 @@ Generator::Run( const string& sCncFile, const std::string& sInfo)
          break ;
       }
      // passo alla operazione successiva
-      nOpId = m_pMchMgr->GetNextOperation( nOpId) ;
+      nOpId = m_pMchMgr->GetNextActiveOperation( nOpId) ;
    }
 
   // evento fine programma
diff --git a/MachMgr.h b/MachMgr.h
index cdbcb7f..ff1cbcd 100644
--- a/MachMgr.h
+++ b/MachMgr.h
@@ -149,11 +149,19 @@ class MachMgr : public IMachMgr
       virtual int  GetNextOperation( int nId) const ;
       virtual int  GetLastOperation( void) const ;
       virtual int  GetPrevOperation( int nId) const ;
+      virtual int  GetFirstActiveOperation( void) const ;
+      virtual int  GetNextActiveOperation( int nId) const ;
+      virtual int  GetLastActiveOperation( void) const ;
+      virtual int  GetPrevActiveOperation( int nId) const ;
       virtual int  GetOperationType( int nId) const ;
       virtual std::string GetOperationName( int nId) const ;
       virtual int  GetOperationId( const std::string& sName) const ;
       virtual bool RemoveOperation( int nId) ;
       virtual bool RemoveAllOperations( bool bExceptFirstDisp) ;
+      virtual bool SetOperationMode( int nId, bool bActive) ;
+      virtual bool SetAllOperationsMode( bool bExceptFirstDisp, bool bActive) ;
+      virtual bool SetOperationStatus( int nId, bool bShow) ;
+      virtual bool SetAllOperationsStatus(bool bExceptFirstDisp,  bool bShow) ;
      // Operations : dispositions
       virtual int  AddDisposition( const std::string& sName) ;
      // Operations : machinings
diff --git a/MachMgrOperations.cpp b/MachMgrOperations.cpp
index 95f5f40..83f0920 100644
--- a/MachMgrOperations.cpp
+++ b/MachMgrOperations.cpp
@@ -95,10 +95,58 @@ MachMgr::GetPrevOperation( int nId) const
    if ( m_pGeomDB->GetParentId( nId) != nOperGrpId)
       return GDB_ID_NULL ;
   // recupero il precedente sottogruppo
-   int nNextId = m_pGeomDB->GetPrevGroup( nId) ;
+   int nPrevId = m_pGeomDB->GetPrevGroup( nId) ;
+   return nPrevId ;
+}
+
+//----------------------------------------------------------------------------
+int
+MachMgr::GetFirstActiveOperation( void) const
+{
+   int nId = GetFirstOperation() ;
+   int nMode ;
+   while ( nId != GDB_ID_NULL  &&
+           m_pGeomDB->GetCalcMode( nId, nMode)  &&  nMode == GDB_MD_HIDDEN)
+      nId = GetNextOperation( nId) ;
+   return nId ;
+}
+
+//----------------------------------------------------------------------------
+int
+MachMgr::GetNextActiveOperation( int nId) const
+{
+   int nNextId = GetNextOperation( nId) ;
+   int nMode ;
+   while ( nNextId != GDB_ID_NULL  &&
+           m_pGeomDB->GetCalcMode( nNextId, nMode)  &&  nMode == GDB_MD_HIDDEN)
+      nNextId = GetNextOperation( nNextId) ;
    return nNextId ;
 }
 
+//----------------------------------------------------------------------------
+int
+MachMgr::GetLastActiveOperation( void) const
+{
+   int nId = GetLastOperation() ;
+   int nMode ;
+   while ( nId != GDB_ID_NULL  &&
+           m_pGeomDB->GetCalcMode( nId, nMode)  &&  nMode == GDB_MD_HIDDEN)
+      nId = GetPrevOperation( nId) ;
+   return nId ;
+}
+
+//----------------------------------------------------------------------------
+int
+MachMgr::GetPrevActiveOperation( int nId) const
+{
+   int nPrevId = GetPrevOperation( nId) ;
+   int nMode ;
+   while ( nPrevId != GDB_ID_NULL  &&
+           m_pGeomDB->GetCalcMode( nPrevId, nMode)  &&  nMode == GDB_MD_HIDDEN)
+      nPrevId = GetPrevOperation( nPrevId) ;
+   return nPrevId ;
+}
+
 //----------------------------------------------------------------------------
 int
 MachMgr::GetOperationType( int nId) const
@@ -217,12 +265,65 @@ MachMgr::RemoveAllOperations( bool bExceptFirstDisp)
   // indice terminazione ciclo
    int nStopId = ( bExceptFirstDisp ? GetFirstOperation() : GDB_ID_NULL) ;
   // rimuovo tutte le operazioni a partire dalla fine
-   int nOperId = GetLastOperation() ;
-   while ( nOperId != nStopId) {
-      RemoveOperation( nOperId) ;
-      nOperId = GetLastOperation() ;
+   int nId = GetLastOperation() ;
+   while ( nId != GDB_ID_NULL  &&  nId != nStopId) {
+      RemoveOperation( nId) ;
+      nId = GetLastOperation() ;
    }
+   return true ;
+}
 
+//----------------------------------------------------------------------------
+bool
+MachMgr::SetOperationMode( int nId, bool bActive)
+{
+  // verifico sia una Operazione
+   if ( GetOperationType( nId) == OPER_NULL)
+      return false ;
+  // eseguo attivazione/disattivazione
+   m_pGeomDB->SetMode( nId, ( bActive ? GDB_MD_STD : GDB_MD_HIDDEN)) ;
+   return true ;
+}
+
+//----------------------------------------------------------------------------
+bool
+MachMgr::SetAllOperationsMode( bool bExceptFirstDisp, bool bActive)
+{
+  // modifico lo stato di tutte le operazioni
+   int nId = ( bExceptFirstDisp ? GetNextOperation( GetFirstOperation()) : GetFirstOperation()) ;
+   while ( nId != GDB_ID_NULL) {
+     // eseguo attivazione/disattivazione
+      m_pGeomDB->SetMode( nId, ( bActive ? GDB_MD_STD : GDB_MD_HIDDEN)) ;
+     // passo alla successiva
+      nId = GetNextOperation( nId) ;
+   }
+   return true ;
+}
+
+//----------------------------------------------------------------------------
+bool
+MachMgr::SetOperationStatus( int nId, bool bShow)
+{
+  // verifico sia una Operazione
+   if ( GetOperationType( nId) == OPER_NULL)
+      return false ;
+  // eseguo cambio di stato di visualizzazione
+   m_pGeomDB->SetStatus( nId, ( bShow ? GDB_ST_ON : GDB_ST_OFF)) ;
+   return true ;
+}
+
+//----------------------------------------------------------------------------
+bool
+MachMgr::SetAllOperationsStatus( bool bExceptFirstDisp, bool bShow)
+{
+  // modifico lo stato di tutte le operazioni
+   int nId = ( bExceptFirstDisp ? GetNextOperation( GetFirstOperation()) : GetFirstOperation()) ;
+   while ( nId != GDB_ID_NULL) {
+     // eseguo cambio di stato di visualizzazione
+      m_pGeomDB->SetStatus( nId, ( bShow ? GDB_ST_ON : GDB_ST_OFF)) ;
+     // passo alla successiva
+      nId = GetNextOperation( nId) ;
+   }
    return true ;
 }
 
diff --git a/Machining.cpp b/Machining.cpp
index 09ea5a0..5e6cebe 100644
--- a/Machining.cpp
+++ b/Machining.cpp
@@ -654,7 +654,7 @@ Machining::AdjustStartMovements(void)
       return false ;
 
   // recupero la lavorazione precedente
-   int nPrevOpId = m_pMchMgr->GetPrevOperation( m_nOwnerId) ;
+   int nPrevOpId = m_pMchMgr->GetPrevActiveOperation( m_nOwnerId) ;
    Machining* pPrevMch = dynamic_cast<Machining*>( m_pGeomDB->GetUserObj( nPrevOpId)) ;
   // recupero l'utensile precedente e i dati della sua testa
    string sPrevTool ;
diff --git a/Sawing.cpp b/Sawing.cpp
index 25d8e26..2da2e0f 100644
--- a/Sawing.cpp
+++ b/Sawing.cpp
@@ -330,6 +330,7 @@ Sawing::Preview( bool bRecalc)
       if ( nAuxId == GDB_ID_NULL)
          return false ;
       m_pGeomDB->SetName( nAuxId, MCH_AUX) ;
+      m_pGeomDB->SetStatus( nAuxId, GDB_ST_OFF) ;
       bChain = true ;
    }
   // altrimenti, se chiesto ricalcolo, lo svuoto
@@ -387,6 +388,7 @@ Sawing::Apply( bool bRecalc)
       if ( nAuxId == GDB_ID_NULL)
          return false ;
       m_pGeomDB->SetName( nAuxId, MCH_AUX) ;
+      m_pGeomDB->SetStatus( nAuxId, GDB_ST_OFF) ;
       bChain = true ;
    }
   // altrimenti, se chiesto ricalcolo, lo svuoto
diff --git a/Simulator.cpp b/Simulator.cpp
index b73ce51..1f989d7 100644
--- a/Simulator.cpp
+++ b/Simulator.cpp
@@ -65,13 +65,13 @@ Simulator::Start( void)
    if ( nMachGrp == GDB_ID_NULL)
       return false ;
   // verifico la disposizione iniziale della macchinata
-   int nOpId = m_pMchMgr->GetFirstOperation() ;
+   int nOpId = m_pMchMgr->GetFirstActiveOperation() ;
    if ( m_pMchMgr->GetOperationType( nOpId) != OPER_DISP)
       return false ;
   // cerco la prima lavorazione
-   nOpId = m_pMchMgr->GetNextOperation( nOpId) ;
+   nOpId = m_pMchMgr->GetNextActiveOperation( nOpId) ;
    while ( nOpId != GDB_ID_NULL  &&  ! IsValidMachiningType( m_pMchMgr->GetOperationType( nOpId)))
-      nOpId = m_pMchMgr->GetNextOperation( nOpId) ;
+      nOpId = m_pMchMgr->GetNextActiveOperation( nOpId) ;
    if ( nOpId == GDB_ID_NULL)
       return false ;
    m_nOpId = nOpId ;
@@ -118,7 +118,7 @@ Simulator::Move( int& nStatus)
    }
   // Se arrivato alla fine di una lavorazione, recupero la successiva
    while ( m_nCLPathId == GDB_ID_NULL) {
-      m_nOpId = m_pMchMgr->GetNextOperation( m_nOpId) ;
+      m_nOpId = m_pMchMgr->GetNextActiveOperation( m_nOpId) ;
      // se non ce ne sono altre, sono alla fine
       if ( m_nOpId == GDB_ID_NULL) {
          nStatus = MCH_SIM_END ;