diff --git a/apps/sample/trimesh_attribute/trimesh_attribute.cpp b/apps/sample/trimesh_attribute/trimesh_attribute.cpp
index 4b36cf4f..71f1ba86 100644
--- a/apps/sample/trimesh_attribute/trimesh_attribute.cpp
+++ b/apps/sample/trimesh_attribute/trimesh_attribute.cpp
@@ -13,44 +13,60 @@ class MyVertex  : public vcg::VertexSimp2< MyVertex, MyEdge, MyFace, vcg::vertex
 class MyFace    : public vcg::FaceSimp2< MyVertex, MyEdge, MyFace, vcg::face::VertexRef, vcg::face::Normal3f> {};
 
 class MyMesh : public vcg::tri::TriMesh< std::vector<MyVertex>, std::vector<MyFace> > {};
-
- 
-float Irradiance(MyMesh::VertexType v){
-	// .....
-	return 1.0;
-}
-
-int main()
-{
-  MyMesh m;
-  //...here m is filled
-  
-  // add a per-vertex attribute with type float named "Irradiance"
-  MyMesh::PerVertexAttributeHandle<float> ih = vcg::tri::Allocator<MyMesh>::AddPerVertexAttribute<float> (m,std::string("Irradiance"));
-
-  // add a per-vertex attribute with type float named "Radiosity"   
-  vcg::tri::Allocator<MyMesh>::AddPerVertexAttribute<float> (m,std::string("Radiosity"));
- 
-  // add a per-vertex attribute with type bool and no name specified
-  MyMesh::PerVertexAttributeHandle<bool> blocked_h = vcg::tri::Allocator<MyMesh>::AddPerVertexAttribute<bool> (m); 
-  
-  MyMesh::VertexIterator vi; int i = 0;
-  for(vi   = m.vert.begin(); vi != m.vert.end(); ++vi,++i){
-   ih[vi]  = Irradiance(*vi);  // [] operator takes a iterator
-   ih[*vi] = Irradiance(*vi);  // or a MyMesh::VertexType object
-   ih[&*vi]= Irradiance(*vi);  // or a pointer to it
-   ih[i]   = Irradiance(*vi);  // or an integer index
-  }
-    
-  // Once created with AddPerVertexAttribute, an handle to the attribute can be obtained as follows
-  MyMesh::PerVertexAttributeHandle<float> rh = vcg::tri::Allocator<MyMesh>::GetPerVertexAttribute<float>(m,"Radiosity");
-
-  // you can query if an attribute is present or not
-  bool hasRadiosity = vcg::tri::HasPerVertexAttribute(m,"Radiosity");
-
-  // you can delete an attibute by name
-  vcg::tri::Allocator<MyMesh>::DeletePerVertexAttribute<float>(m,"Radiosity");
-
-  // you can delete an attibute by handle
-  vcg::tri::Allocator<MyMesh>::DeletePerVertexAttribute<bool>(m,blocked_h);
-}
+
+ 
+float Irradiance(MyMesh::VertexType v){
+	// .....
+	return 1.0;
+}
+
+int main()
+{
+
+
+  MyMesh m;
+  //...here m is filled
+  
+  // add a per-vertex attribute with type float named "Irradiance"
+  MyMesh::PerVertexAttributeHandle<float> ih = vcg::tri::Allocator<MyMesh>::AddPerVertexAttribute<float> (m,std::string("Irradiance"));
+
+  // add a per-vertex attribute with type float named "Radiosity"   
+  vcg::tri::Allocator<MyMesh>::AddPerVertexAttribute<float> (m,std::string("Radiosity"));
+ 
+  // add a per-vertex attribute with type bool and no name specified
+  MyMesh::PerVertexAttributeHandle<bool> blocked_h = vcg::tri::Allocator<MyMesh>::AddPerVertexAttribute<bool> (m); 
+  
+  // add a per-vertex attribute with type bool and no name specified
+  MyMesh::PerFaceAttributeHandle<bool> blocked_hf = vcg::tri::Allocator<MyMesh>::AddPerFaceAttribute<bool> (m); 
+
+  MyMesh::VertexIterator vi; int i = 0;
+  for(vi   = m.vert.begin(); vi != m.vert.end(); ++vi,++i){
+   ih[vi]  = Irradiance(*vi);  // [] operator takes a iterator
+   ih[*vi] = Irradiance(*vi);  // or a MyMesh::VertexType object
+   ih[&*vi]= Irradiance(*vi);  // or a pointer to it
+   ih[i]   = Irradiance(*vi);  // or an integer index
+  }
+    
+  // Once created with AddPerVertexAttribute, an handle to the attribute can be obtained as follows
+  MyMesh::PerVertexAttributeHandle<float> rh = vcg::tri::Allocator<MyMesh>::GetPerVertexAttribute<float>(m,"Radiosity");
+
+  // you can query if an attribute is present or not
+  bool hasRadiosity = vcg::tri::HasPerVertexAttribute(m,"Radiosity");
+
+  // you can delete an attibute by name
+  vcg::tri::Allocator<MyMesh>::DeletePerVertexAttribute(m,"Radiosity");
+
+  // you can delete an attibute by handle
+  vcg::tri::Allocator<MyMesh>::DeletePerVertexAttribute(m,blocked_h);
+
+  bool res ;
+ 
+  res = vcg::tri::Allocator<MyMesh>::IsValidHandle(m,ih);printf("%d\n",res);
+  res = vcg::tri::Allocator<MyMesh>::IsValidHandle(m,blocked_hf);printf("%d\n",res);
+  vcg::tri::Allocator<MyMesh>::DeletePerVertexAttribute(m,ih);
+  vcg::tri::Allocator<MyMesh>::DeletePerFaceAttribute(m,blocked_hf);
+  res = vcg::tri::Allocator<MyMesh>::IsValidHandle(m,ih);printf("%d\n",res);
+  res = vcg::tri::Allocator<MyMesh>::IsValidHandle(m,blocked_hf);printf("%d\n",res);
+
+ 
+}