diff --git a/Mesh_3/demo/Mesh_3/CMakeLists.txt b/Mesh_3/demo/Mesh_3/CMakeLists.txt
index 6405f3f7e30..8038e9a6a91 100644
--- a/Mesh_3/demo/Mesh_3/CMakeLists.txt
+++ b/Mesh_3/demo/Mesh_3/CMakeLists.txt
@@ -95,6 +95,7 @@ if((QT4 OR QT5) AND OPENGL_FOUND AND QGLVIEWER_FOUND AND Boost_FOUND)
   qt_wrap_ui( funcUI_FILES  ui_files/Function_dialog.ui)
   qt_wrap_ui( imgUI_FILES ui_files/Image_res_dialog.ui)
 
+
   include(AddFileDependencies)
 
   # Shared demo files directory
@@ -232,14 +233,24 @@ if(QT4)
 
   add_definitions(-DUSE_FORWARD_DECL)
   add_definitions(-DQT_STATICPLUGIN)
-    add_executable  ( Mesh_3 MainWindow.cpp
+ 
+ if(QT4)
+  add_executable  ( Mesh_3 MainWindow.cpp
       Mesh_3.cpp
       ${DEMO_SRC_DIR}/Scene.cpp
       MainWindow_moc.cpp
       Scene_moc.cpp
       ${UI_FILES} ${RESOURCE_FILES} )
     add_to_cached_list( CGAL_EXECUTABLE_TARGETS Mesh_3 )
-
+ endif(QT4)
+ if(QT5)
+  add_executable  ( Mesh_3 MainWindow.cpp
+      Mesh_3.cpp
+      ${DEMO_SRC_DIR}/Scene.cpp
+      Scene_moc.cpp
+      ${UI_FILES} ${RESOURCE_FILES} )
+    add_to_cached_list( CGAL_EXECUTABLE_TARGETS Mesh_3 )
+ endif(QT5)
   # Link with Qt libraries
   target_link_libraries( Mesh_3 ${QT_LIBRARIES} )
 
@@ -275,12 +286,8 @@ if(QT4)
     qt_generate_moc( "${CMAKE_CURRENT_SOURCE_DIR}/${plugin_implementation_base_name}.cpp" ${plugin_implementation_base_name}.moc )
     add_file_dependencies( ${plugin_implementation_base_name}.moc "${CMAKE_CURRENT_SOURCE_DIR}/${plugin_implementation_base_name}.cpp" )
 
-    if(QT5)
-     add_library(${plugin_name} MODULE ${option} ${plugin_implementation_base_name}.cpp)
-    endif()
-    if(QT4)
-     add_library(${plugin_name} MODULE ${option} ${plugin_implementation_base_name}.moc ${plugin_implementation_base_name}.cpp ${other_sources})
-    endif()
+    add_library(${plugin_name} MODULE ${option} ${plugin_implementation_base_name}.moc ${plugin_implementation_base_name}.cpp ${other_sources})
+
     add_to_cached_list( CGAL_EXECUTABLE_TARGETS ${plugin_name} )
     # Link with Qt
     target_link_libraries( ${plugin_name} ${QT_LIBRARIES} )
diff --git a/Mesh_3/demo/Mesh_3/Io_c3t3_plugin.cpp b/Mesh_3/demo/Mesh_3/Io_c3t3_plugin.cpp
index 3025ac10af1..73929def818 100644
--- a/Mesh_3/demo/Mesh_3/Io_c3t3_plugin.cpp
+++ b/Mesh_3/demo/Mesh_3/Io_c3t3_plugin.cpp
@@ -3,6 +3,7 @@
 #include <CGAL_demo/Io_plugin_interface.h>
 #include <fstream>
 
+
 class Io_c3t3_plugin :
   public QObject,
   public Io_plugin_interface
@@ -10,6 +11,10 @@ class Io_c3t3_plugin :
   Q_OBJECT
   Q_INTERFACES(Io_plugin_interface)
 
+  #if QT_VERSION >= 0x050000
+  Q_PLUGIN_METADATA(IID "com.geometryfactory.PolyhedronDemo.IOPluginInterface/1.0")//New for Qt5 version !
+  #endif
+
 public:
   virtual QStringList nameFilters() const;
   
@@ -20,7 +25,6 @@ public:
   virtual bool save(const Scene_item*, QFileInfo fileinfo);
 };
 
-
 QStringList
 Io_c3t3_plugin::nameFilters() const
 { 
@@ -51,7 +55,8 @@ Io_c3t3_plugin::save(const Scene_item* item, QFileInfo fileInfo)
   return true;
 }
 
-
+#if QT_VERSION < 0x050000
 #include <QtPlugin>
 Q_EXPORT_PLUGIN2(Io_c3t3_plugin, Io_c3t3_plugin)
+#endif
 #include "Io_c3t3_plugin.moc"
diff --git a/Mesh_3/demo/Mesh_3/Io_image_plugin.cpp b/Mesh_3/demo/Mesh_3/Io_image_plugin.cpp
index f8a78b5b613..ff2eeb31e65 100644
--- a/Mesh_3/demo/Mesh_3/Io_image_plugin.cpp
+++ b/Mesh_3/demo/Mesh_3/Io_image_plugin.cpp
@@ -15,6 +15,10 @@ class Io_image_plugin :
   Q_OBJECT
   Q_INTERFACES(Io_plugin_interface)
 
+  #if QT_VERSION >= 0x050000
+  Q_PLUGIN_METADATA(IID "com.geometryfactory.PolyhedronDemo.IOPluginInterface/1.0")//New for Qt5 version !
+  #endif
+
 public:
   Io_image_plugin() {
 #ifdef SCENE_SEGMENTED_IMAGE_GL_BUFFERS_AVAILABLE
@@ -30,6 +34,7 @@ public:
   bool save(const Scene_item*, QFileInfo) { return false; }
 };
 
+
 QStringList Io_image_plugin::nameFilters() const {
   return QStringList() << "Inrimage files (*.inr *.inr.gz)"
                        << "Analyze files (*.hdr *.img *img.gz)"
@@ -87,6 +92,8 @@ bool Io_image_plugin::canSave(const Scene_item*)
   return false;
 }
 
+#if QT_VERSION < 0x050000
 #include <QtPlugin>
 Q_EXPORT_PLUGIN2(Io_image_plugin, Io_image_plugin)
+#endif
 #include "Io_image_plugin.moc"
diff --git a/Mesh_3/demo/Mesh_3/Io_implicit_function_plugin.cpp b/Mesh_3/demo/Mesh_3/Io_implicit_function_plugin.cpp
index fbcd9e371d7..4b4ea00a83e 100644
--- a/Mesh_3/demo/Mesh_3/Io_implicit_function_plugin.cpp
+++ b/Mesh_3/demo/Mesh_3/Io_implicit_function_plugin.cpp
@@ -39,13 +39,17 @@
 #include <QList>
 #include <QLibrary>
 
+
 class Io_implicit_function_plugin :
   public QObject,
   protected Plugin_helper
 {
   Q_OBJECT
   Q_INTERFACES(Plugin_interface)
-  
+
+  #if QT_VERSION >= 0x050000
+  Q_PLUGIN_METADATA(IID "com.geometryfactory.PolyhedronDemo.PluginInterface/1.0")//New for Qt5 version !
+  #endif
 public:
   Io_implicit_function_plugin();
   virtual ~Io_implicit_function_plugin() {}
@@ -196,7 +200,8 @@ load_function_plugins()
   }
 }
 
-
+#if QT_VERSION < 0x050000
 #include <QtPlugin>
 Q_EXPORT_PLUGIN2(Io_implicit_function_plugin, Io_implicit_function_plugin)
+#endif
 #include "Io_implicit_function_plugin.moc"
diff --git a/Mesh_3/demo/Mesh_3/Io_off_plugin.cpp b/Mesh_3/demo/Mesh_3/Io_off_plugin.cpp
index 87aa44f1659..38eec192e81 100644
--- a/Mesh_3/demo/Mesh_3/Io_off_plugin.cpp
+++ b/Mesh_3/demo/Mesh_3/Io_off_plugin.cpp
@@ -5,6 +5,7 @@
 #include <CGAL_demo/Io_plugin_interface.h>
 #include <fstream>
 
+
 class Io_off_plugin :
   public QObject,
   public Io_plugin_interface
@@ -12,6 +13,9 @@ class Io_off_plugin :
   Q_OBJECT
   Q_INTERFACES(Io_plugin_interface)
 
+  #if QT_VERSION >= 0x050000
+  Q_PLUGIN_METADATA(IID "com.geometryfactory.PolyhedronDemo.IOPluginInterface/1.0")//New for Qt5 version !
+  #endif
 public:
   QStringList nameFilters() const;
   bool canLoad() const;
@@ -85,7 +89,8 @@ bool Io_off_plugin::save(const Scene_item* item, QFileInfo fileinfo)
   return (poly_item && poly_item->save(out)) || 
     (soup_item && soup_item->save(out));
 }
-
+#if QT_VERSION < 0x050000
 #include <QtPlugin>
 Q_EXPORT_PLUGIN2(Io_off_plugin, Io_off_plugin)
+#endif
 #include "Io_off_plugin.moc"
diff --git a/Mesh_3/demo/Mesh_3/Mesh_3_optimization_plugin.cpp b/Mesh_3/demo/Mesh_3/Mesh_3_optimization_plugin.cpp
index 2ed1a48e647..d64fd36ca5f 100644
--- a/Mesh_3/demo/Mesh_3/Mesh_3_optimization_plugin.cpp
+++ b/Mesh_3/demo/Mesh_3/Mesh_3_optimization_plugin.cpp
@@ -32,7 +32,6 @@
 #include <CGAL/Mesh_optimization_return_code.h>
 #include <CGAL/Mesh_3/parameters_defaults.h> // to get default values
 
-
 // declare the CGAL function
 Optimizer_thread* cgal_code_odt_mesh_3(Scene_c3t3_item& c3t3_item,
                                        const double time_limit,
@@ -60,6 +59,7 @@ Optimizer_thread* cgal_code_exude_mesh_3(Scene_c3t3_item& c3t3_item,
 
 QString translate(CGAL::Mesh_optimization_return_code rc);
 
+
 // Mesh_3_optimization_plugin class
 class Mesh_3_optimization_plugin : 
   public QObject,
@@ -68,6 +68,10 @@ class Mesh_3_optimization_plugin :
   Q_OBJECT
   Q_INTERFACES(Plugin_interface)
   
+  #if QT_VERSION >= 0x050000
+  Q_PLUGIN_METADATA(IID "com.geometryfactory.PolyhedronDemo.PluginInterface/1.0")//New for Qt5 version !
+  #endif
+
   typedef Plugin_helper Base;
 public:
   Mesh_3_optimization_plugin();
@@ -104,7 +108,6 @@ private:
   Scene_c3t3_item* source_item_;
 }; // end class Mesh_3_optimization_plugin
 
-
 Mesh_3_optimization_plugin::
 Mesh_3_optimization_plugin()
   : actionOdt(NULL)
@@ -584,7 +587,9 @@ translate(CGAL::Mesh_optimization_return_code rc)
 }
 
 
+#if QT_VERSION < 0x050000
 Q_EXPORT_PLUGIN2(Mesh_3_optimization_plugin, Mesh_3_optimization_plugin)
+#endif
 
 #include "Mesh_3_optimization_plugin.moc"
 
diff --git a/Mesh_3/demo/Mesh_3/Mesh_3_plugin.cpp b/Mesh_3/demo/Mesh_3/Mesh_3_plugin.cpp
index 5974295b0c7..1383e524193 100644
--- a/Mesh_3/demo/Mesh_3/Mesh_3_plugin.cpp
+++ b/Mesh_3/demo/Mesh_3/Mesh_3_plugin.cpp
@@ -34,6 +34,7 @@
 #include <fstream>
 #include <math.h>
 
+
 // Constants
 const QColor default_mesh_color(45,169,70);
 
@@ -62,14 +63,17 @@ Meshing_thread* cgal_code_mesh_3(const Implicit_function_interface*,
 double get_approximate(double d, int precision, int& decimals);
 
 
-
 class Mesh_3_plugin : 
   public QObject,
   protected Plugin_helper
 {
   Q_OBJECT
   Q_INTERFACES(Plugin_interface)
-  
+
+  #if QT_VERSION >= 0x050000
+  Q_PLUGIN_METADATA(IID "com.geometryfactory.PolyhedronDemo.PluginInterface/1.0")//New for Qt5 version !
+  #endif
+
   typedef Plugin_helper Base;
 public:
   Mesh_3_plugin();
@@ -112,6 +116,7 @@ private:
   
 }; // end class Mesh_3_plugin
 
+
 Mesh_3_plugin::
 Mesh_3_plugin()
   : actionMesh_3(NULL)
@@ -404,7 +409,8 @@ get_approximate(double d, int precision, int& decimals)
   return std::floor(d)*std::pow(10.,decimals);
 }
 
-
+#if QT_VERSION < 0x050000
 Q_EXPORT_PLUGIN2(Mesh_3_plugin, Mesh_3_plugin)
+#endif
 
 #include "Mesh_3_plugin.moc"
diff --git a/Mesh_3/demo/Mesh_3/implicit_functions/Klein_implicit_function.cpp b/Mesh_3/demo/Mesh_3/implicit_functions/Klein_implicit_function.cpp
index aa480e952df..c1e8b57fa81 100644
--- a/Mesh_3/demo/Mesh_3/implicit_functions/Klein_implicit_function.cpp
+++ b/Mesh_3/demo/Mesh_3/implicit_functions/Klein_implicit_function.cpp
@@ -31,7 +31,11 @@ class Klein_implicit_function :
 {
   Q_OBJECT
   Q_INTERFACES(Implicit_function_interface)
-  
+
+  #if QT_VERSION >= 0x050000
+  Q_PLUGIN_METADATA(IID "com.geometryfactory.Mesh3Demo.Implicit_function_interface/1.0")//New for Qt5 version !
+  #endif
+
 public:
   virtual QString name() const { return "Klein function"; }
   
@@ -50,6 +54,10 @@ public:
   }
 };
 
+
+#if QT_VERSION < 0x050000
 #include <QtPlugin>
 Q_EXPORT_PLUGIN2(Klein_implicit_function, Klein_implicit_function)
+#endif
+
 #include "Klein_implicit_function.moc"
diff --git a/Mesh_3/demo/Mesh_3/implicit_functions/Sphere_implicit_function.cpp b/Mesh_3/demo/Mesh_3/implicit_functions/Sphere_implicit_function.cpp
index bb02a0887ac..fe1091d7102 100644
--- a/Mesh_3/demo/Mesh_3/implicit_functions/Sphere_implicit_function.cpp
+++ b/Mesh_3/demo/Mesh_3/implicit_functions/Sphere_implicit_function.cpp
@@ -25,7 +25,6 @@
 #include <QObject>
 #include "Implicit_function_interface.h"
 
-
 const double radius = 1.;
 
 class Sphere_implicit_function :
@@ -34,7 +33,11 @@ class Sphere_implicit_function :
 {
   Q_OBJECT
   Q_INTERFACES(Implicit_function_interface)
-  
+
+  #if QT_VERSION >= 0x050000
+  Q_PLUGIN_METADATA(IID "com.geometryfactory.Mesh3Demo.Implicit_function_interface/1.0")//New for Qt5 version !
+  #endif
+
 public:
   virtual QString name() const { return "Sphere function"; }
   
@@ -51,7 +54,9 @@ public:
 };
 
 
-
+#if QT_VERSION < 0x050000
 #include <QtPlugin>
 Q_EXPORT_PLUGIN2(Sphere_implicit_function, Sphere_implicit_function)
+#endif
+
 #include "Sphere_implicit_function.moc"
diff --git a/Mesh_3/demo/Mesh_3/implicit_functions/Tanglecube_implicit_function.cpp b/Mesh_3/demo/Mesh_3/implicit_functions/Tanglecube_implicit_function.cpp
index b092fa25fb6..95f82761132 100644
--- a/Mesh_3/demo/Mesh_3/implicit_functions/Tanglecube_implicit_function.cpp
+++ b/Mesh_3/demo/Mesh_3/implicit_functions/Tanglecube_implicit_function.cpp
@@ -25,7 +25,6 @@
 #include <QObject>
 #include "Implicit_function_interface.h"
 
-
 const double radius = 4.;
 
 class Tanglecube_implicit_function :
@@ -35,6 +34,10 @@ class Tanglecube_implicit_function :
   Q_OBJECT
   Q_INTERFACES(Implicit_function_interface)
   
+  #if QT_VERSION >= 0x050000
+  Q_PLUGIN_METADATA(IID "com.geometryfactory.Mesh3Demo.Implicit_function_interface/1.0")//New for Qt5 version !
+  #endif
+
 public:
   virtual QString name() const { return "Tanglecube function"; }
   
@@ -53,7 +56,9 @@ public:
 };
 
 
-
+#if QT_VERSION < 0x050000
 #include <QtPlugin>
 Q_EXPORT_PLUGIN2(Tanglecube_implicit_function, Tanglecube_implicit_function)
+#endif
+
 #include "Tanglecube_implicit_function.moc"
diff --git a/Mesh_3/demo/Mesh_3/include/CGAL_demo/Io_plugin_interface.h b/Mesh_3/demo/Mesh_3/include/CGAL_demo/Io_plugin_interface.h
index 625cb969e13..736bbf8bb4a 100644
--- a/Mesh_3/demo/Mesh_3/include/CGAL_demo/Io_plugin_interface.h
+++ b/Mesh_3/demo/Mesh_3/include/CGAL_demo/Io_plugin_interface.h
@@ -4,6 +4,7 @@
 #include <QFileInfo>
 #include <QStringList>
 
+
 class Scene_item;
 
 class Io_plugin_interface 
diff --git a/Mesh_3/demo/Mesh_3/src/CGAL_demo/Plugin_helper.cpp b/Mesh_3/demo/Mesh_3/src/CGAL_demo/Plugin_helper.cpp
index 8b9535be8f1..25967ec934c 100644
--- a/Mesh_3/demo/Mesh_3/src/CGAL_demo/Plugin_helper.cpp
+++ b/Mesh_3/demo/Mesh_3/src/CGAL_demo/Plugin_helper.cpp
@@ -54,8 +54,13 @@ void Plugin_helper::autoConnectActions()
       i < metaObject->methodCount();
       ++i)
   {
+#if QT_VERSION >= 0x050000
+    const int pos = QString(metaObject->method(i).methodSignature()).indexOf('(');
+    methodsNames << QString(metaObject->method(i).methodSignature()).left(pos);
+#else
     const int pos = QString(metaObject->method(i).signature()).indexOf('(');
     methodsNames << QString(metaObject->method(i).signature()).left(pos);
+#endif
     methods << metaObject->method(i);
   }
 
@@ -72,13 +77,42 @@ void Plugin_helper::autoConnectActions()
         
       if(action_method.methodType() == QMetaMethod::Signal)
       {
+#if QT_VERSION >= 0x050000
+        const int pos = QString(action_method.methodSignature()).indexOf('(');
+        QString methodName = QString(action_method.methodSignature()).left(pos);
+#else
         const int pos = QString(action_method.signature()).indexOf('(');
         QString methodName = QString(action_method.signature()).left(pos);
+#endif
         QString slotName = 
           QString("on_%1_%2").arg(action->objectName()).arg(methodName);
 //         qDebug() << thisObject->tr("Slot %1 (%2)...").arg(slotName).arg(i);
         int index = methodsNames.indexOf(slotName);
-        if(index>=0 && !connected.contains(slotName)) {
+  
+#if QT_VERSION >= 0x050000      
+	if(index>=0 && !connected.contains(slotName)) 
+	{
+          const bool ok = 
+            QObject::connect(action, 
+                             qPrintable(QString("2%1").arg(QString(action_method.methodSignature()))),
+                             thisObject,
+                             qPrintable(QString("1%1").arg(QString(methods[index].methodSignature()))));
+          if(!ok)
+          {
+            qDebug() << thisObject->tr("Cannot connect method %1.%2 to slot %3!")
+              .arg(action->objectName())
+              .arg(QString(action_method.methodSignature()))
+              .arg(QString(methods[index].methodSignature()));
+          }
+          else {
+//             qDebug("  ->Connected!");
+            success = true;
+            connected << slotName;
+          }
+        }
+#else
+	if(index>=0 && !connected.contains(slotName)) 
+	{
           const bool ok = 
             QObject::connect(action, 
                              qPrintable(QString("2%1").arg(action_method.signature())),
@@ -97,6 +131,7 @@ void Plugin_helper::autoConnectActions()
             connected << slotName;
           }
         }
+#endif
 //         else {
 //           qDebug(" nothing found!\n");
 //         }