diff --git a/Polyhedron/demo/Polyhedron/Scene.cpp b/Polyhedron/demo/Polyhedron/Scene.cpp
index 14d68665495..d667f6196f4 100644
--- a/Polyhedron/demo/Polyhedron/Scene.cpp
+++ b/Polyhedron/demo/Polyhedron/Scene.cpp
@@ -90,6 +90,8 @@ Scene::addItem(CGAL::Three::Scene_item* item)
     item->drawEdges(CGAL::Three::Three::mainViewer());
     item->drawPoints(CGAL::Three::Three::mainViewer());
     CGAL::Three::Three::mainViewer()->setDepthPeelingFbo(fbo);
+    if(group)
+       m_groups.append(id);
     return id;
 }
 
@@ -110,6 +112,7 @@ Scene::replaceItem(Scene::Item_id index, CGAL::Three::Scene_item* item, bool emi
     QList<Scene_item*> group_children;
     if(group)
     {
+      m_groups.removeAll(index);
       Q_FOREACH(Item_id id, group->getChildren())
       {
         CGAL::Three::Scene_item* child = group->getChild(id);
@@ -152,6 +155,7 @@ Scene::replaceItem(Scene::Item_id index, CGAL::Three::Scene_item* item, bool emi
     if(group)
     {
         addGroup(group);
+        m_groups.append(index);
     }
     itemChanged(index);
     Q_EMIT restoreCollapsedState();
@@ -173,6 +177,7 @@ Scene::erase(Scene::Item_id index)
     setSelectedItemsList(QList<Scene_interface::Item_id>()<<item_id(item));
     return erase(selectionIndices());
   }
+  m_groups.removeAll(index);
   if(item->parentGroup()
      && item->parentGroup()->isChildLocked(item))
     return -1;
@@ -248,6 +253,7 @@ Scene::erase(QList<int> indices)
       item->parentGroup()->removeChild(item);
     children.removeAll(removed_item);
     indexErased(removed_item);
+    m_groups.removeAll(removed_item);
     m_entries.removeAll(item);
 
     Q_EMIT itemAboutToBeDestroyed(item);
@@ -1344,9 +1350,15 @@ QItemSelection Scene::createSelectionAll()
   //it is not possible to directly create a selection with items that have different parents, so
   //we do it iteratively.
   QItemSelection sel;
-  for(int i=0; i< m_entries.size(); ++i)
-    sel.select(index_map.keys(i).at(0),
-               index_map.keys(i).at(4));
+  sel.select(this->createIndex(0, 0),
+             this->createIndex(m_entries.size(), LastColumn));
+  for(const auto& gid : m_groups)
+  {
+    CGAL::Three::Scene_group_item* group =
+        qobject_cast<CGAL::Three::Scene_group_item*>(item(gid));
+    sel.select(index_map.keys(group->getChildren().first()).at(0),
+               index_map.keys(group->getChildren().last()).at(4));
+  }
   return sel;
 }
 
diff --git a/Polyhedron/demo/Polyhedron/Scene.h b/Polyhedron/demo/Polyhedron/Scene.h
index 6240a255abf..61010a23513 100644
--- a/Polyhedron/demo/Polyhedron/Scene.h
+++ b/Polyhedron/demo/Polyhedron/Scene.h
@@ -64,6 +64,7 @@ public:
   int numberOfEntries() const Q_DECL_OVERRIDE;
   // returns the list of items.
   const QList<CGAL::Three::Scene_item*>& entries() const { return m_entries; }
+
   Q_INVOKABLE CGAL::Three::Scene_item* item(int) const Q_DECL_OVERRIDE;
   int item_id(CGAL::Three::Scene_item*) const Q_DECL_OVERRIDE;
 
@@ -280,6 +281,7 @@ private:
   typedef QList<CGAL::Three::Scene_item*> Entries;
   //List containing all the scene_items.
   Entries m_entries;
+  QList<Item_id> m_groups; //used to optimize createSelectionAll()
   QList<Item_id> children;
   // Index of the currently selected item.
   int selected_item;