diff --git a/src/board/UBBoardController.cpp b/src/board/UBBoardController.cpp
index 0b640e07..bffbf4a2 100644
--- a/src/board/UBBoardController.cpp
+++ b/src/board/UBBoardController.cpp
@@ -1552,60 +1552,55 @@ void UBBoardController::moveSceneToIndex(int source, int target)
 
 void UBBoardController::ClearUndoStack()
 {
-// The code has been removed because it leads to a strange error and because the final goal has never been
-// reached on tests and sound a little bit strange.
-// Strange error: item->scene() crashes the application because item doesn't implement scene() method. I'm
-// not able to give all the steps to reproduce this error sistematically but is quite frequent (~ twice per utilisation hours)
-// strange goal: if item is on the undocommand, the item->scene() is null and the item is not on the deleted scene item list then
-// then it's deleted.
-
-    //    QSet<QGraphicsItem*> uniqueItems;
-//    // go through all stack command
-//    for(int i = 0; i < UBApplication::undoStack->count(); i++)
-//    {
-
-//        UBAbstractUndoCommand *abstractCmd = (UBAbstractUndoCommand*)UBApplication::undoStack->command(i);
-//        if(abstractCmd->getType() != UBAbstractUndoCommand::undotype_GRAPHICITEM)
-//            continue;
-
-//        UBGraphicsItemUndoCommand *cmd = (UBGraphicsItemUndoCommand*)UBApplication::undoStack->command(i);
-
-//        // go through all added and removed objects, for create list of unique objects
-//        // grouped items will be deleted by groups, so we don't need do delete that items.
-//        QSetIterator<QGraphicsItem*> itAdded(cmd->GetAddedList());
-//        while (itAdded.hasNext())
-//        {
-//            QGraphicsItem* item = itAdded.next();
-//            if( !uniqueItems.contains(item) && !(item->parentItem() && UBGraphicsGroupContainerItem::Type == item->parentItem()->type()))
-//                uniqueItems.insert(item);
-//        }
-
-//        QSetIterator<QGraphicsItem*> itRemoved(cmd->GetRemovedList());
-//        while (itRemoved.hasNext())
-//        {
-//            QGraphicsItem* item = itRemoved.next();
-//            if( !uniqueItems.contains(item) && !(item->parentItem() && UBGraphicsGroupContainerItem::Type == item->parentItem()->type()))
-//                uniqueItems.insert(item);
-//        }
-//    }
-
-//    // go through all unique items, and check, ot on scene, or not.
-//    // if not on scene, than item can be deleted
-
-//    QSetIterator<QGraphicsItem*> itUniq(uniqueItems);
-//    while (itUniq.hasNext())
-//    {
-//        QGraphicsItem* item = itUniq.next();
-//        UBGraphicsScene *scene = NULL;
-//        if (item->scene()) {
-//            scene = dynamic_cast<UBGraphicsScene*>(item->scene());
-//        }
-//        if(!scene)
-//        {
-//           if (!mActiveScene->deleteItem(item))
-//               delete item;
-//        }
-//    }
+    QSet<QGraphicsItem*> uniqueItems;
+    // go through all stack command
+    for(int i = 0; i < UBApplication::undoStack->count(); i++)
+    {
+
+        UBAbstractUndoCommand *abstractCmd = (UBAbstractUndoCommand*)UBApplication::undoStack->command(i);
+        if(abstractCmd->getType() != UBAbstractUndoCommand::undotype_GRAPHICITEM)
+            continue;
+
+        UBGraphicsItemUndoCommand *cmd = (UBGraphicsItemUndoCommand*)UBApplication::undoStack->command(i);
+
+        // go through all added and removed objects, for create list of unique objects
+        // grouped items will be deleted by groups, so we don't need do delete that items.
+        QSetIterator<QGraphicsItem*> itAdded(cmd->GetAddedList());
+        while (itAdded.hasNext())
+        {
+            QGraphicsItem* item = itAdded.next();
+            if( !uniqueItems.contains(item) && !(item->parentItem() && UBGraphicsGroupContainerItem::Type == item->parentItem()->type()))
+                uniqueItems.insert(item);
+        }
+
+        QSetIterator<QGraphicsItem*> itRemoved(cmd->GetRemovedList());
+        while (itRemoved.hasNext())
+        {
+            QGraphicsItem* item = itRemoved.next();
+            if( !uniqueItems.contains(item) && !(item->parentItem() && UBGraphicsGroupContainerItem::Type == item->parentItem()->type()))
+                uniqueItems.insert(item);
+        }
+    }
+
+    // go through all unique items, and check, if they are on scene, or not.
+    // if not on scene, than item can be deleted
+
+    QSetIterator<QGraphicsItem*> itUniq(uniqueItems);
+    while (itUniq.hasNext())
+    {
+        QGraphicsItem* item = itUniq.next();
+        UBGraphicsScene *scene = NULL;
+        if (item->scene()) {
+            scene = dynamic_cast<UBGraphicsScene*>(item->scene());
+        }
+        if(!scene)
+        {
+            if (!mActiveScene->deleteItem(item)){
+                delete item;
+                item = 0;
+            }
+        }
+    }
 
     // clear stack, and command list
     UBApplication::undoStack->clear();
diff --git a/src/core/UBApplication.h b/src/core/UBApplication.h
index 6f76c1db..1649d0fc 100644
--- a/src/core/UBApplication.h
+++ b/src/core/UBApplication.h
@@ -47,7 +47,7 @@ class UBMainWindow;
 
 class UBApplication : public QtSingleApplication
 {
-    Q_OBJECT;
+    Q_OBJECT
 
     public:
 
diff --git a/src/domain/UBGraphicsItemUndoCommand.cpp b/src/domain/UBGraphicsItemUndoCommand.cpp
index 1fb1bd3d..bcad7056 100644
--- a/src/domain/UBGraphicsItemUndoCommand.cpp
+++ b/src/domain/UBGraphicsItemUndoCommand.cpp
@@ -221,7 +221,7 @@ void UBGraphicsItemUndoCommand::redo()
 
                 UBGraphicsPolygonItem *polygonItem = qgraphicsitem_cast<UBGraphicsPolygonItem*>(item);
                 if (polygonItem)
-                {   
+                {
                     mScene->removeItem(polygonItem);
                     mScene->removeItemFromDeletion(polygonItem);
                     polygonItem->strokesGroup()->addToGroup(polygonItem);