diff --git a/AABB_tree/demo/AABB_tree/AABB_demo.cpp b/AABB_tree/demo/AABB_tree/AABB_demo.cpp
index c69f7aa1281..018e0f69c14 100644
--- a/AABB_tree/demo/AABB_tree/AABB_demo.cpp
+++ b/AABB_tree/demo/AABB_tree/AABB_demo.cpp
@@ -19,18 +19,16 @@
 #include <QApplication>
 #include <CGAL/Qt/resources.h>
 #include <QMimeData>
-
+#include <CGAL/Qt/init_ogl_context.h>
 
 int main(int argc, char **argv)
 {
+
+  CGAL::Qt::init_ogl_context(4,3);
   QApplication app(argc, argv);
   app.setOrganizationDomain("inria.fr");
   app.setOrganizationName("INRIA");
   app.setApplicationName("AABB tree demo");
-  //for windows
-#if (QT_VERSION >= QT_VERSION_CHECK(5, 3, 0))
-  app.setAttribute(Qt::AA_UseDesktopOpenGL);
-#endif
 
   // Import resources from libCGALQt (Qt5).
   CGAL_QT_INIT_RESOURCES;
diff --git a/AABB_tree/demo/AABB_tree/MainWindow.cpp b/AABB_tree/demo/AABB_tree/MainWindow.cpp
index c5d00c638bb..78a8336f076 100644
--- a/AABB_tree/demo/AABB_tree/MainWindow.cpp
+++ b/AABB_tree/demo/AABB_tree/MainWindow.cpp
@@ -45,6 +45,7 @@ MainWindow::MainWindow(QWidget* parent)
 
 MainWindow::~MainWindow()
 {
+  m_pViewer->makeCurrent();
   delete ui;
 }
 
diff --git a/AABB_tree/demo/AABB_tree/Scene.cpp b/AABB_tree/demo/AABB_tree/Scene.cpp
index 69ba683a21b..b86be7ca292 100644
--- a/AABB_tree/demo/AABB_tree/Scene.cpp
+++ b/AABB_tree/demo/AABB_tree/Scene.cpp
@@ -91,8 +91,8 @@ void Scene::compile_shaders()
     //Vertex source code
     const char vertex_source[] =
     {
-        "#version 120 \n"
-        "attribute highp vec4 vertex;\n"
+        "#version 150 \n"
+        "in highp vec4 vertex;\n"
         "uniform highp mat4 mvp_matrix;\n"
         "uniform highp mat4 f_matrix;\n"
         "void main(void)\n"
@@ -103,10 +103,11 @@ void Scene::compile_shaders()
     //Vertex source code
     const char fragment_source[] =
     {
-        "#version 120 \n"
+        "#version 150 \n"
         "uniform highp vec4 color; \n"
+        "out highp vec4 out_color; \n"
         "void main(void) { \n"
-        "gl_FragColor = color; \n"
+        "out_color = color; \n"
         "} \n"
         "\n"
     };
@@ -139,26 +140,27 @@ void Scene::compile_shaders()
     //Vertex source code
     const char tex_vertex_source[] =
     {
-        "#version 120 \n"
-        "attribute highp vec4 vertex;\n"
-        "attribute highp vec2 tex_coord; \n"
+        "#version 150 \n"
+        "in highp vec4 vertex;\n"
+        "in highp vec2 tex_coord; \n"
         "uniform highp mat4 mvp_matrix;\n"
         "uniform highp mat4 f_matrix;\n"
-        "varying highp vec2 texc;\n"
+        "out highp vec2 texc;\n"
         "void main(void)\n"
         "{\n"
         "   gl_Position = mvp_matrix * f_matrix * vertex;\n"
-        "    texc = tex_coord;\n"
+        "   texc = tex_coord;\n"
         "}"
     };
     //Vertex source code
     const char tex_fragment_source[] =
     {
-        "#version 120 \n"
-        "uniform sampler2D texture;\n"
-        "varying highp vec2 texc;\n"
+        "#version 150 \n"
+        "uniform sampler2D s_texture;\n"
+        "in highp vec2 texc;\n"
+        "out highp vec4 out_color; \n"
         "void main(void) { \n"
-        "gl_FragColor = texture2D(texture, texc.st);\n"
+        "out_color = vec4(texture(s_texture, texc));\n"
         "} \n"
         "\n"
     };
@@ -1319,12 +1321,8 @@ void Scene::deactivate_cutting_plane()
 }
 void Scene::initGL()
 {
-    gl = new QOpenGLFunctions_2_1();
-   if(!gl->initializeOpenGLFunctions())
-    {
-        qFatal("ERROR : OpenGL Functions not initialized. Check your OpenGL Verison (should be >=3.3)");
-        exit(1);
-    }
+    gl = new QOpenGLFunctions();
+    gl->initializeOpenGLFunctions();
 
     gl->glGenTextures(1, &textureId);
     compile_shaders();
diff --git a/AABB_tree/demo/AABB_tree/Scene.h b/AABB_tree/demo/AABB_tree/Scene.h
index 95ea74cdc33..44d7b8239ce 100644
--- a/AABB_tree/demo/AABB_tree/Scene.h
+++ b/AABB_tree/demo/AABB_tree/Scene.h
@@ -86,7 +86,7 @@ public:
 
 private:
     // member data
-    QOpenGLFunctions_2_1 *gl;
+    QOpenGLFunctions *gl;
     Bbox m_bbox;
     Polyhedron *m_pPolyhedron;
     std::list<Point> m_points;
diff --git a/Alpha_shapes_3/demo/Alpha_shapes_3/Alpha_shape_3.cpp b/Alpha_shapes_3/demo/Alpha_shapes_3/Alpha_shape_3.cpp
index dbe053e9824..784ee1af57f 100644
--- a/Alpha_shapes_3/demo/Alpha_shapes_3/Alpha_shape_3.cpp
+++ b/Alpha_shapes_3/demo/Alpha_shapes_3/Alpha_shape_3.cpp
@@ -5,18 +5,16 @@
 
 
 #include <CGAL/Qt/resources.h>
+#include <CGAL/Qt/init_ogl_context.h>
 
 int main(int argc, char** argv)
 {
- QApplication application(argc,argv);
+  CGAL::Qt::init_ogl_context(4,3);
 
+  QApplication application(argc,argv);
   application.setOrganizationDomain("geometryfactory.com");
   application.setOrganizationName("GeometryFactory");
   application.setApplicationName("Alpha Shape Reconstruction");
-  //for Windows
-#if (QT_VERSION >= QT_VERSION_CHECK(5, 3, 0))
-  application.setAttribute(Qt::AA_UseDesktopOpenGL);
-#endif
 
   // Import resources from libCGALQt (Qt5).
   // See https://doc.qt.io/qt-5/qdir.html#Q_INIT_RESOURCE
diff --git a/Alpha_shapes_3/demo/Alpha_shapes_3/Viewer.cpp b/Alpha_shapes_3/demo/Alpha_shapes_3/Viewer.cpp
index a30e7a9a133..ad0e388412c 100644
--- a/Alpha_shapes_3/demo/Alpha_shapes_3/Viewer.cpp
+++ b/Alpha_shapes_3/demo/Alpha_shapes_3/Viewer.cpp
@@ -29,14 +29,14 @@ void Viewer::compile_shaders()
     //Vertex source code
     const char vertex_source[] =
     {
-         "#version 120 \n"
-        "attribute highp vec4 vertex;\n"
-        "attribute highp vec3 normal;\n"
+         "#version 150 \n"
+        "in highp vec4 vertex;\n"
+        "in highp vec3 normal;\n"
 
         "uniform highp mat4 mvp_matrix;\n"
         "uniform highp mat4 mv_matrix; \n"
-        "varying highp vec4 fP; \n"
-        "varying highp vec3 fN; \n"
+        "out highp vec4 fP; \n"
+        "out highp vec3 fN; \n"
         "void main(void)\n"
         "{\n"
         "   fP = mv_matrix * vertex; \n"
@@ -47,15 +47,16 @@ void Viewer::compile_shaders()
     //Fragment source code
     const char fragment_source[] =
     {
-        "#version 120 \n"
-        "varying highp vec4 fP; \n"
-        "varying highp vec3 fN; \n"
+        "#version 150 \n"
+        "in highp vec4 fP; \n"
+        "in highp vec3 fN; \n"
         "uniform highp vec4 color; \n"
         "uniform highp vec4 light_pos;  \n"
         "uniform highp vec4 light_diff; \n"
         "uniform highp vec4 light_spec; \n"
         "uniform highp vec4 light_amb;  \n"
         "uniform float spec_power ; \n"
+        "out highp vec4 out_color; \n"
 
         "void main(void) { \n"
 
@@ -70,7 +71,7 @@ void Viewer::compile_shaders()
         "   highp vec4 diffuse = abs(dot(N,L)) * light_diff * color; \n"
         "   highp vec4 specular = pow(max(dot(R,V), 0.0), spec_power) * light_spec; \n"
 
-        "gl_FragColor = light_amb*color + diffuse + specular ; \n"
+        "out_color = light_amb*color + diffuse + specular ; \n"
         "} \n"
         "\n"
     };
@@ -105,8 +106,8 @@ rendering_program.bind();
 //Vertex source code
 const char vertex_source_points[] =
 {
-    "#version 120 \n"
-    "attribute highp vec4 vertex;\n"
+    "#version 150 \n"
+    "in highp vec4 vertex;\n"
 
     "uniform highp mat4 mvp_matrix;\n"
     "uniform highp float point_size;\n"
@@ -119,11 +120,12 @@ const char vertex_source_points[] =
 //Vertex source code
 const char fragment_source_points[] =
 {
-    "#version 120 \n"
+    "#version 150 \n"
     "uniform highp vec4 color; \n"
+    "out highp vec4 out_color; \n"
 
     "void main(void) { \n"
-    "gl_FragColor = color; \n"
+    "out_color = color; \n"
     "} \n"
     "\n"
 };
diff --git a/Alpha_shapes_3/demo/Alpha_shapes_3/Viewer.h b/Alpha_shapes_3/demo/Alpha_shapes_3/Viewer.h
index ff19159d837..289ae385c1e 100644
--- a/Alpha_shapes_3/demo/Alpha_shapes_3/Viewer.h
+++ b/Alpha_shapes_3/demo/Alpha_shapes_3/Viewer.h
@@ -21,6 +21,7 @@ public:
   Viewer(QWidget* parent);
   ~Viewer()
   {
+    makeCurrent();
     buffers[0].destroy();
     buffers[1].destroy();
     buffers[2].destroy();
diff --git a/Circular_kernel_3/demo/Circular_kernel_3/Circular_kernel_3.cpp b/Circular_kernel_3/demo/Circular_kernel_3/Circular_kernel_3.cpp
index 513722fec61..0b41052abad 100644
--- a/Circular_kernel_3/demo/Circular_kernel_3/Circular_kernel_3.cpp
+++ b/Circular_kernel_3/demo/Circular_kernel_3/Circular_kernel_3.cpp
@@ -1,17 +1,12 @@
 #include "Viewer.h"
 #include <qapplication.h>
-
+#include <CGAL/Qt/init_ogl_context.h>
 int main(int argc, char** argv)
 {
-  // Read command lines arguments.
+  CGAL::Qt::init_ogl_context(4,3);
   QApplication application(argc,argv);
-
   // Instantiate the viewer.
   Viewer viewer;
-  //for Windows
-#if (QT_VERSION >= QT_VERSION_CHECK(5, 3, 0))
-  application.setAttribute(Qt::AA_UseDesktopOpenGL);
-#endif
   viewer.setWindowTitle("Intersection points of randomly generated circles.");
 
   // Make the viewer window visible on screen.
diff --git a/Circular_kernel_3/demo/Circular_kernel_3/Viewer.cpp b/Circular_kernel_3/demo/Circular_kernel_3/Viewer.cpp
index c026e1cce0b..aa5a06c1354 100644
--- a/Circular_kernel_3/demo/Circular_kernel_3/Viewer.cpp
+++ b/Circular_kernel_3/demo/Circular_kernel_3/Viewer.cpp
@@ -11,6 +11,14 @@ Viewer::Viewer(QWidget* parent )
 {
     extension_is_found = false;
 }
+Viewer::~Viewer()
+{
+  makeCurrent();
+  for(int i=0; i<3; ++i)
+    vao[i].destroy();
+  for(int i=0; i<9; ++i)
+    buffers[i].destroy();
+}
 
 void Viewer::compile_shaders()
 {
@@ -32,16 +40,16 @@ void Viewer::compile_shaders()
     //Vertex source code
     const char vertex_source[] =
     {
-        "#version 120 \n"
-        "attribute highp vec4 vertex;\n"
-        "attribute highp vec3 normal;\n"
-        "attribute highp vec4 center;\n"
+        "#version 150 \n"
+        "in highp vec4 vertex;\n"
+        "in highp vec3 normal;\n"
+        "in highp vec4 center;\n"
 
         "uniform highp mat4 mvp_matrix;\n"
         "uniform highp mat4 mv_matrix; \n"
 
-        "varying highp vec4 fP; \n"
-        "varying highp vec3 fN; \n"
+        "out highp vec4 fP; \n"
+        "out highp vec3 fN; \n"
         "void main(void)\n"
         "{\n"
         "   fP = mv_matrix * vertex; \n"
@@ -52,15 +60,16 @@ void Viewer::compile_shaders()
     //Vertex source code
     const char fragment_source[] =
     {
-        "#version 120 \n"
-        "varying highp vec4 fP; \n"
-        "varying highp vec3 fN; \n"
+        "#version 150 \n"
+        "in highp vec4 fP; \n"
+        "in highp vec3 fN; \n"
         "uniform highp vec4 color; \n"
         "uniform highp vec4 light_pos;  \n"
         "uniform highp vec4 light_diff; \n"
         "uniform highp vec4 light_spec; \n"
         "uniform highp vec4 light_amb;  \n"
         "uniform float spec_power ; \n"
+        "out highp vec4 out_color; \n"
 
         "void main(void) { \n"
 
@@ -75,7 +84,7 @@ void Viewer::compile_shaders()
         "   highp vec4 diffuse = max(dot(N,L), 0.0) * light_diff * color; \n"
         "   highp vec4 specular = pow(max(dot(R,V), 0.0), spec_power) * light_spec; \n"
 
-        "gl_FragColor = light_amb*color + diffuse  ; \n"
+        "out_color = light_amb*color + diffuse  ; \n"
         "} \n"
         "\n"
     };
@@ -111,8 +120,8 @@ void Viewer::compile_shaders()
              //Vertex source code
              const char vertex_source_no_ext[] =
              {
-                 "#version 120 \n"
-                 "attribute highp vec4 vertex;\n"
+                 "#version 150 \n"
+                 "in highp vec4 vertex;\n"
                  "uniform highp mat4 mvp_matrix;\n"
                  "void main(void)\n"
                  "{\n"
@@ -123,10 +132,11 @@ void Viewer::compile_shaders()
              //Vertex source code
              const char fragment_source_no_ext[] =
              {
-                 "#version 120 \n"
+                 "#version 150 \n"
                  "uniform highp vec4 color; \n"
+                 "out highp vec4 out_color; \n"
                  "void main(void) { \n"
-                 "gl_FragColor = color; \n"
+                 "out_color = color; \n"
                  "} \n"
                  "\n"
              };
diff --git a/Circular_kernel_3/demo/Circular_kernel_3/Viewer.h b/Circular_kernel_3/demo/Circular_kernel_3/Viewer.h
index ea178e756a0..cad037ce2c8 100644
--- a/Circular_kernel_3/demo/Circular_kernel_3/Viewer.h
+++ b/Circular_kernel_3/demo/Circular_kernel_3/Viewer.h
@@ -13,6 +13,7 @@ class Viewer : public CGAL::QGLViewer
 {
 public:
     Viewer(QWidget* parent = 0);
+    ~Viewer();
   GLuint dl_nb;
 protected :
   virtual void draw();
diff --git a/GraphicsView/include/CGAL/Qt/Basic_viewer_qt.h b/GraphicsView/include/CGAL/Qt/Basic_viewer_qt.h
index 11058fe04e6..37462215e41 100644
--- a/GraphicsView/include/CGAL/Qt/Basic_viewer_qt.h
+++ b/GraphicsView/include/CGAL/Qt/Basic_viewer_qt.h
@@ -54,21 +54,20 @@
 
 namespace CGAL
 {
-
 //------------------------------------------------------------------------------
 const char vertex_source_color[] =
   {
-    "#version 120 \n"
-    "attribute highp vec4 vertex;\n"
-    "attribute highp vec3 normal;\n"
-    "attribute highp vec3 color;\n"
+    "#version 150 \n"
+    "in highp vec4 vertex;\n"
+    "in highp vec3 normal;\n"
+    "in highp vec3 color;\n"
 
     "uniform highp mat4 mvp_matrix;\n"
     "uniform highp mat4 mv_matrix; \n"
 
-    "varying highp vec4 fP; \n"
-    "varying highp vec3 fN; \n"
-    "varying highp vec4 fColor; \n"
+    "out highp vec4 fP; \n"
+    "out highp vec3 fN; \n"
+    "out highp vec4 fColor; \n"
 
     "uniform highp float point_size; \n"
     "void main(void)\n"
@@ -83,15 +82,16 @@ const char vertex_source_color[] =
 
 const char fragment_source_color[] =
   {
-    "#version 120 \n"
-    "varying highp vec4 fP; \n"
-    "varying highp vec3 fN; \n"
-    "varying highp vec4 fColor; \n"
+    "#version 150 \n"
+    "in highp vec4 fP; \n"
+    "in highp vec3 fN; \n"
+    "in highp vec4 fColor; \n"
     "uniform highp vec4 light_pos;  \n"
     "uniform highp vec4 light_diff; \n"
     "uniform highp vec4 light_spec; \n"
     "uniform highp vec4 light_amb;  \n"
     "uniform float spec_power ; \n"
+    "out vec4 out_color; \n"
 
     "void main(void) { \n"
     "   highp vec3 L = light_pos.xyz - fP.xyz; \n"
@@ -104,18 +104,18 @@ const char fragment_source_color[] =
     "   highp vec3 R = reflect(-L, N); \n"
     "   highp vec4 diffuse = max(dot(N,L), 0.0) * light_diff * fColor; \n"
     "   highp vec4 specular = pow(max(dot(R,V), 0.0), spec_power) * light_spec; \n"
-    "   gl_FragColor = light_amb*fColor + diffuse  ; \n"
+    "   out_color = light_amb*fColor + diffuse  ; \n"
     "} \n"
     "\n"
   };
 
 const char vertex_source_p_l[] =
   {
-    "#version 120 \n"
-    "attribute highp vec4 vertex;\n"
-    "attribute highp vec3 color;\n"
+    "#version 150 \n"
+    "in highp vec4 vertex;\n"
+    "in highp vec3 color;\n"
     "uniform highp mat4 mvp_matrix;\n"
-    "varying highp vec4 fColor; \n"
+    "out highp vec4 fColor; \n"
     "uniform highp float point_size; \n"
     "void main(void)\n"
     "{\n"
@@ -127,10 +127,11 @@ const char vertex_source_p_l[] =
 
 const char fragment_source_p_l[] =
   {
-    "#version 120 \n"
-    "varying highp vec4 fColor; \n"
+    "#version 150 \n"
+    "in highp vec4 fColor; \n"
+    "out vec4 out_color; \n"
     "void main(void) { \n"
-    "gl_FragColor = fColor; \n"
+    "out_color = fColor; \n"
     "} \n"
     "\n"
   };
@@ -358,6 +359,7 @@ public:
 
   ~Basic_viewer_qt()
   {
+    makeCurrent();
     for (unsigned int i=0; i<NB_VBO_BUFFERS; ++i)
       buffers[i].destroy();
 
diff --git a/GraphicsView/include/CGAL/Qt/init_ogl_context.h b/GraphicsView/include/CGAL/Qt/init_ogl_context.h
new file mode 100644
index 00000000000..4ec18c6659a
--- /dev/null
+++ b/GraphicsView/include/CGAL/Qt/init_ogl_context.h
@@ -0,0 +1,53 @@
+// Copyright (c) 2021  GeometryFactory Sarl (France).
+// All rights reserved.
+//
+// This file is part of CGAL (www.cgal.org).
+//
+// $URL$
+// $Id$
+// SPDX-License-Identifier: GPL-3.0-or-later OR LicenseRef-Commercial
+//
+//
+// Author(s)     : Maxime Gimeno
+
+#ifndef CGAL_QT_CONTEXT_INITIALIZATION_H
+#define CGAL_QT_CONTEXT_INITIALIZATION_H
+
+#include <CGAL/license/GraphicsView.h>
+
+
+#include <QSurfaceFormat>
+#include <QCoreApplication>
+namespace CGAL
+{
+namespace Qt
+{
+inline void init_ogl_context(int major, int minor) {
+  QSurfaceFormat fmt;
+#ifdef Q_OS_MAC
+  if(major == 4)
+  {
+    fmt.setVersion(4, 1);
+  }
+  else
+  {
+     fmt.setVersion(major, minor);
+  }
+#else
+  fmt.setVersion(major, minor);
+#endif
+  fmt.setRenderableType(QSurfaceFormat::OpenGL);
+  fmt.setProfile(QSurfaceFormat::CoreProfile);
+  fmt.setOption(QSurfaceFormat::DebugContext);
+  QSurfaceFormat::setDefaultFormat(fmt);
+
+  //for windows
+  QCoreApplication::setAttribute(::Qt::AA_UseDesktopOpenGL);
+
+  //We set the locale to avoid any trouble with VTK
+  setlocale(LC_ALL, "C");
+}
+
+} //end Qt
+} //end CGAL
+#endif // CGAL_QT_CONTEXT_INITIALIZATION_H
diff --git a/GraphicsView/include/CGAL/Qt/qglviewer_impl.h b/GraphicsView/include/CGAL/Qt/qglviewer_impl.h
index 865f7b63a1f..7032ba5225e 100644
--- a/GraphicsView/include/CGAL/Qt/qglviewer_impl.h
+++ b/GraphicsView/include/CGAL/Qt/qglviewer_impl.h
@@ -217,16 +217,6 @@ void CGAL::QGLViewer::initializeGL() {
          || QCoreApplication::arguments().contains(QStringLiteral("--old")))
 
     {
-      format.setDepthBufferSize(24);
-      format.setStencilBufferSize(8);
-      format.setVersion(2,0);
-      format.setRenderableType(QSurfaceFormat::OpenGLES);
-      format.setSamples(0);
-      format.setOption(QSurfaceFormat::DebugContext);
-      QSurfaceFormat::setDefaultFormat(format);
-
-      needNewContext();
-      qDebug()<<"GL 4.3 context initialization failed. ";
       is_ogl_4_3 = false;
     }
     else
diff --git a/Linear_cell_complex/demo/Linear_cell_complex/Linear_cell_complex_3_demo.cpp b/Linear_cell_complex/demo/Linear_cell_complex/Linear_cell_complex_3_demo.cpp
index 42713752435..cd31d859217 100644
--- a/Linear_cell_complex/demo/Linear_cell_complex/Linear_cell_complex_3_demo.cpp
+++ b/Linear_cell_complex/demo/Linear_cell_complex/Linear_cell_complex_3_demo.cpp
@@ -14,6 +14,7 @@
 #include <QApplication>
 #include <CGAL/Qt/resources.h>
 #include <CGAL/assertions_behaviour.h>
+#include <CGAL/Qt/init_ogl_context.h>
 
 // Global random
 CGAL::Random myrandom;
@@ -23,15 +24,12 @@ int main(int argc, char** argv)
   // std::cout<<"Size of dart: "<<sizeof(LCC::Dart)<<std::endl;
   CGAL::set_error_behaviour(CGAL::ABORT);
 
+  CGAL::Qt::init_ogl_context(4,3);
   QApplication application(argc,argv);
 
   application.setOrganizationDomain("cgal.org");
   application.setOrganizationName("CNRS and LIRIS' Establishments");
   application.setApplicationName("3D Linear Cell Complex");
-  //for windows
-#if (QT_VERSION >= QT_VERSION_CHECK(5, 3, 0))
-  application.setAttribute(Qt::AA_UseDesktopOpenGL);
-#endif
 
   // Import resources from libCGALQt5
   // See https://doc.qt.io/qt-5/qdir.html#Q_INIT_RESOURCE
diff --git a/Linear_cell_complex/examples/Linear_cell_complex/basic_viewer.h b/Linear_cell_complex/examples/Linear_cell_complex/basic_viewer.h
index db5a49f847f..b6b89a1b416 100644
--- a/Linear_cell_complex/examples/Linear_cell_complex/basic_viewer.h
+++ b/Linear_cell_complex/examples/Linear_cell_complex/basic_viewer.h
@@ -17,7 +17,7 @@
 
 #include <CGAL/Qt/qglviewer.h>
 #include <QKeyEvent>
-#include <QOpenGLFunctions_2_1>
+#include <QOpenGLFunctions>
 #include <QOpenGLVertexArrayObject>
 #include <QGLBuffer>
 #include <QOpenGLShaderProgram>
@@ -43,15 +43,15 @@ typedef Local_kernel::Vector_3 Local_vector;
 //Vertex source code
 const char vertex_source_mono[] =
   {
-    "#version 120 \n"
-    "attribute highp vec4 vertex;\n"
-    "attribute highp vec3 normal;\n"
+    "#version 150 \n"
+    "in highp vec4 vertex;\n"
+    "in highp vec3 normal;\n"
 
     "uniform highp mat4 mvp_matrix;\n"
     "uniform highp mat4 mv_matrix; \n"
 
-    "varying highp vec4 fP; \n"
-    "varying highp vec3 fN; \n"
+    "out highp vec4 fP; \n"
+    "out highp vec3 fN; \n"
     "void main(void)\n"
     "{\n"
     "   fP = mv_matrix * vertex; \n"
@@ -62,17 +62,17 @@ const char vertex_source_mono[] =
 
 const char vertex_source_color[] =
   {
-    "#version 120 \n"
-    "attribute highp vec4 vertex;\n"
-    "attribute highp vec3 normal;\n"
-    "attribute highp vec3 color;\n"
+    "#version 150 \n"
+    "in highp vec4 vertex;\n"
+    "in highp vec3 normal;\n"
+    "in highp vec3 color;\n"
 
     "uniform highp mat4 mvp_matrix;\n"
     "uniform highp mat4 mv_matrix; \n"
 
-    "varying highp vec4 fP; \n"
-    "varying highp vec3 fN; \n"
-    "varying highp vec4 fColor; \n"
+    "out highp vec4 fP; \n"
+    "out highp vec3 fN; \n"
+    "out highp vec4 fColor; \n"
     "void main(void)\n"
     "{\n"
     "   fP = mv_matrix * vertex; \n"
@@ -85,15 +85,16 @@ const char vertex_source_color[] =
 //Vertex source code
 const char fragment_source_mono[] =
   {
-    "#version 120 \n"
-    "varying highp vec4 fP; \n"
-    "varying highp vec3 fN; \n"
+    "#version 150 \n"
+    "in highp vec4 fP; \n"
+    "in highp vec3 fN; \n"
     "uniform highp vec4 color; \n"
     "uniform highp vec4 light_pos;  \n"
     "uniform highp vec4 light_diff; \n"
     "uniform highp vec4 light_spec; \n"
     "uniform highp vec4 light_amb;  \n"
     "uniform float spec_power ; \n"
+    "out highp vec4 out_color; \n"
 
     "void main(void) { \n"
 
@@ -108,22 +109,23 @@ const char fragment_source_mono[] =
     "   highp vec4 diffuse = max(dot(N,L), 0.0) * light_diff * color; \n"
     "   highp vec4 specular = pow(max(dot(R,V), 0.0), spec_power) * light_spec; \n"
 
-    "gl_FragColor = light_amb*color + diffuse  ; \n"
+    "out_color = light_amb*color + diffuse  ; \n"
     "} \n"
     "\n"
   };
 
 const char fragment_source_color[] =
   {
-    "#version 120 \n"
-    "varying highp vec4 fP; \n"
-    "varying highp vec3 fN; \n"
-    "varying highp vec4 fColor; \n"
+    "#version 150 \n"
+    "in highp vec4 fP; \n"
+    "in highp vec3 fN; \n"
+    "in highp vec4 fColor; \n"
     "uniform highp vec4 light_pos;  \n"
     "uniform highp vec4 light_diff; \n"
     "uniform highp vec4 light_spec; \n"
     "uniform highp vec4 light_amb;  \n"
     "uniform float spec_power ; \n"
+    "out highp vec4 out_color; \n"
 
     "void main(void) { \n"
 
@@ -138,7 +140,7 @@ const char fragment_source_color[] =
     "   highp vec4 diffuse = max(dot(N,L), 0.0) * light_diff * fColor; \n"
     "   highp vec4 specular = pow(max(dot(R,V), 0.0), spec_power) * light_spec; \n"
 
-    "gl_FragColor = light_amb*fColor + diffuse  ; \n"
+    "out_color = light_amb*fColor + diffuse  ; \n"
     "} \n"
     "\n"
   };
@@ -146,8 +148,8 @@ const char fragment_source_color[] =
 //Vertex source code
 const char vertex_source_p_l[] =
   {
-    "#version 120 \n"
-    "attribute highp vec4 vertex;\n"
+    "#version 150 \n"
+    "in highp vec4 vertex;\n"
     "uniform highp mat4 mvp_matrix;\n"
     "void main(void)\n"
     "{\n"
@@ -157,10 +159,11 @@ const char vertex_source_p_l[] =
 //Vertex source code
 const char fragment_source_p_l[] =
   {
-    "#version 120 \n"
+    "#version 150 \n"
     "uniform highp vec4 color; \n"
+    "out highp vec4 out_color; \n"
     "void main(void) { \n"
-    "gl_FragColor = color; \n"
+    "out_color = color; \n"
     "} \n"
     "\n"
   };
@@ -194,7 +197,7 @@ typename K::Vector_3 compute_normal_of_face(const std::vector<typename K::Point_
   return (typename K::Construct_scaled_vector_3()(normal, 1.0/nb));
 }
 
-class Basic_viewer : public CGAL::QGLViewer, public QOpenGLFunctions_2_1
+class Basic_viewer : public CGAL::QGLViewer, public QOpenGLFunctions
 {
   struct Vertex_info
   {
diff --git a/Linear_cell_complex/include/CGAL/draw_linear_cell_complex.h b/Linear_cell_complex/include/CGAL/draw_linear_cell_complex.h
index 706735aa87a..49383d6f5eb 100644
--- a/Linear_cell_complex/include/CGAL/draw_linear_cell_complex.h
+++ b/Linear_cell_complex/include/CGAL/draw_linear_cell_complex.h
@@ -15,6 +15,7 @@
 #include <CGAL/Qt/Basic_viewer_qt.h>
 
 #ifdef CGAL_USE_BASIC_VIEWER
+#include <CGAL/Qt/init_ogl_context.h>
 
 #include <CGAL/Linear_cell_complex_operations.h>
 #include <CGAL/Random.h>
@@ -405,6 +406,7 @@ void draw(const CGAL_LCC_TYPE& alcc,
 
   if (!cgal_test_suite)
   {
+    CGAL::Qt::init_ogl_context(4,3);
     int argc=1;
     const char* argv[2]={"lccviewer","\0"};
     QApplication app(argc,const_cast<char**>(argv));
diff --git a/Nef_3/include/CGAL/draw_nef_3.h b/Nef_3/include/CGAL/draw_nef_3.h
index da8e01bacc8..bcdb6c61ae3 100644
--- a/Nef_3/include/CGAL/draw_nef_3.h
+++ b/Nef_3/include/CGAL/draw_nef_3.h
@@ -18,6 +18,7 @@
 
 #ifdef CGAL_USE_BASIC_VIEWER
 
+#include <CGAL/Qt/init_ogl_context.h>
 #include <CGAL/Nef_3/SNC_iteration.h>
 #include <CGAL/circulator.h>
 #include <CGAL/Random.h>
@@ -253,6 +254,7 @@ void draw(const CGAL_NEF3_TYPE &anef,
 
   if (!cgal_test_suite)
   {
+    CGAL::Qt::init_ogl_context(4,3);
     int argc = 1;
     const char *argv[2] = {"nef_polyhedron_viewer", "\0"};
     QApplication app(argc, const_cast<char **>(argv));
diff --git a/Periodic_2_triangulation_2/include/CGAL/draw_periodic_2_triangulation_2.h b/Periodic_2_triangulation_2/include/CGAL/draw_periodic_2_triangulation_2.h
index 909b38c0675..e4859ea033f 100644
--- a/Periodic_2_triangulation_2/include/CGAL/draw_periodic_2_triangulation_2.h
+++ b/Periodic_2_triangulation_2/include/CGAL/draw_periodic_2_triangulation_2.h
@@ -17,6 +17,7 @@
 
 #ifdef CGAL_USE_BASIC_VIEWER
 
+#include <CGAL/Qt/init_ogl_context.h>
 #include <CGAL/Exact_predicates_inexact_constructions_kernel.h>
 #include <CGAL/Random.h>
 
@@ -260,6 +261,7 @@ void draw(const CGAL_P2T2_TYPE& ap2t2,
 
   if (!cgal_test_suite)
   {
+    CGAL::Qt::init_ogl_context(4,3);
     int argc=1;
     const char* argv[2]={"p2t2_viewer","\0"};
     QApplication app(argc,const_cast<char**>(argv));
diff --git a/Periodic_3_triangulation_3/demo/Periodic_3_triangulation_3/Scene.h b/Periodic_3_triangulation_3/demo/Periodic_3_triangulation_3/Scene.h
index 41d4311ebe8..32f3926c802 100644
--- a/Periodic_3_triangulation_3/demo/Periodic_3_triangulation_3/Scene.h
+++ b/Periodic_3_triangulation_3/demo/Periodic_3_triangulation_3/Scene.h
@@ -76,6 +76,7 @@ public:
   }
 
   ~Scene() {
+    ui->viewer->makeCurrent();
     for(int i=0; i<24; i++)
         buffers[i].destroy();
     for(int i=0; i<12; i++)
diff --git a/Periodic_3_triangulation_3/demo/Periodic_3_triangulation_3/periodic_3_triangulation_3_demo.cpp b/Periodic_3_triangulation_3/demo/Periodic_3_triangulation_3/periodic_3_triangulation_3_demo.cpp
index c93f4155487..2cf672fdb48 100644
--- a/Periodic_3_triangulation_3/demo/Periodic_3_triangulation_3/periodic_3_triangulation_3_demo.cpp
+++ b/Periodic_3_triangulation_3/demo/Periodic_3_triangulation_3/periodic_3_triangulation_3_demo.cpp
@@ -1,9 +1,11 @@
 #include "MainWindow.h"
 
 #include <QApplication>
+#include <CGAL/Qt/init_ogl_context.h>
 
 int main(int argc, char *argv[])
 {
+  CGAL::Qt::init_ogl_context(2,1);
   QApplication a(argc, argv);
   MainWindow w;
   //w.ui->setupUi(w);
diff --git a/Periodic_3_triangulation_3/demo/Periodic_Lloyd_3/Periodic_Lloyd_3.cpp b/Periodic_3_triangulation_3/demo/Periodic_Lloyd_3/Periodic_Lloyd_3.cpp
index 75f1f8ee396..ae0074e0bcc 100644
--- a/Periodic_3_triangulation_3/demo/Periodic_Lloyd_3/Periodic_Lloyd_3.cpp
+++ b/Periodic_3_triangulation_3/demo/Periodic_Lloyd_3/Periodic_Lloyd_3.cpp
@@ -1,18 +1,17 @@
 #include "MainWindow.h"
 #include <QApplication>
 #include <CGAL/Qt/resources.h>
+#include <CGAL/Qt/init_ogl_context.h>
 
 int main(int argc, char** argv)
 {
-  QApplication application(argc,argv);
 
+  CGAL::Qt::init_ogl_context(2, 1);
+
+  QApplication application(argc,argv);
   application.setOrganizationDomain("inria.fr");
   application.setOrganizationName("INRIA");
   application.setApplicationName("3D Periodic Lloyd");
-  //for windows
-#if (QT_VERSION >= QT_VERSION_CHECK(5, 3, 0))
-  application.setAttribute(Qt::AA_UseDesktopOpenGL);
-#endif
 
   // Import resources from libCGAL (QT5).
   // See https://doc.qt.io/qt-5/qdir.html#Q_INIT_RESOURCE
diff --git a/Periodic_3_triangulation_3/demo/Periodic_Lloyd_3/Viewer.h b/Periodic_3_triangulation_3/demo/Periodic_Lloyd_3/Viewer.h
index 1ea4397cf4c..7ba3534a6d2 100644
--- a/Periodic_3_triangulation_3/demo/Periodic_Lloyd_3/Viewer.h
+++ b/Periodic_3_triangulation_3/demo/Periodic_Lloyd_3/Viewer.h
@@ -27,6 +27,7 @@ public:
   {}
   ~Viewer()
   {
+    makeCurrent();
    for(int i=0; i<4; i++)
    {
     buffers[i].destroy();
diff --git a/Point_set_3/include/CGAL/draw_point_set_3.h b/Point_set_3/include/CGAL/draw_point_set_3.h
index de9548c6b1b..510ba937a0c 100644
--- a/Point_set_3/include/CGAL/draw_point_set_3.h
+++ b/Point_set_3/include/CGAL/draw_point_set_3.h
@@ -35,6 +35,7 @@ void draw(const PS& aps);
 
 #ifdef CGAL_USE_BASIC_VIEWER
 
+#include <CGAL/Qt/init_ogl_context.h>
 #include <CGAL/Point_set_3.h>
 #include <CGAL/Random.h>
 
@@ -100,6 +101,7 @@ void draw(const Point_set_3<P, V>& apointset,
 
   if (!cgal_test_suite)
   {
+    CGAL::Qt::init_ogl_context(4,3);
     int argc=1;
     const char* argv[2]={"point_set_viewer","\0"};
     QApplication app(argc,const_cast<char**>(argv));
diff --git a/Polygon/include/CGAL/draw_polygon_2.h b/Polygon/include/CGAL/draw_polygon_2.h
index 0f75db09b7c..60522c9263d 100644
--- a/Polygon/include/CGAL/draw_polygon_2.h
+++ b/Polygon/include/CGAL/draw_polygon_2.h
@@ -38,7 +38,7 @@ void draw(const P& ap);
 #endif
 
 #ifdef CGAL_USE_BASIC_VIEWER
-
+#include <CGAL/Qt/init_ogl_context.h>
 #include <CGAL/Polygon_2.h>
 #include <CGAL/Random.h>
 
@@ -122,6 +122,7 @@ void draw(const CGAL::Polygon_2<T, C>& ap2,
 
   if (!cgal_test_suite)
   {
+    CGAL::Qt::init_ogl_context(4,3);
     int argc=1;
     const char* argv[2]={"t2_viewer","\0"};
     QApplication app(argc,const_cast<char**>(argv));
diff --git a/Polygon/include/CGAL/draw_polygon_with_holes_2.h b/Polygon/include/CGAL/draw_polygon_with_holes_2.h
index 35f98928c7e..0781eb883f7 100644
--- a/Polygon/include/CGAL/draw_polygon_with_holes_2.h
+++ b/Polygon/include/CGAL/draw_polygon_with_holes_2.h
@@ -37,7 +37,7 @@ void draw(const PH& aph);
 #endif
 
 #ifdef CGAL_USE_BASIC_VIEWER
-
+#include <CGAL/Qt/init_ogl_context.h>
 #include <CGAL/Polygon_with_holes_2.h>
 #include <CGAL/Random.h>
 
@@ -138,6 +138,7 @@ void draw(const CGAL::Polygon_with_holes_2<T, C>& ap2,
 
   if (!cgal_test_suite)
   {
+    CGAL::Qt::init_ogl_context(4,3);
     int argc=1;
     const char* argv[2]={"t2_viewer","\0"};
     QApplication app(argc,const_cast<char**>(argv));
diff --git a/Polyhedron/demo/Polyhedron/Viewer.cpp b/Polyhedron/demo/Polyhedron/Viewer.cpp
index f7811021212..f62ea120333 100644
--- a/Polyhedron/demo/Polyhedron/Viewer.cpp
+++ b/Polyhedron/demo/Polyhedron/Viewer.cpp
@@ -380,6 +380,7 @@ Viewer::Viewer(QWidget* parent,
 
 Viewer::~Viewer()
 {
+  makeCurrent();
     QSettings viewer_settings;
     viewer_settings.setValue("cam_pos",
                              QString("%1,%2,%3")
diff --git a/Polyhedron/include/CGAL/draw_polyhedron.h b/Polyhedron/include/CGAL/draw_polyhedron.h
index d13a66dbbec..e5220aa58f3 100644
--- a/Polyhedron/include/CGAL/draw_polyhedron.h
+++ b/Polyhedron/include/CGAL/draw_polyhedron.h
@@ -16,7 +16,7 @@
 #include <CGAL/Qt/Basic_viewer_qt.h>
 
 #ifdef CGAL_USE_BASIC_VIEWER
-
+#include <CGAL/Qt/init_ogl_context.h>
 #include <CGAL/Polyhedron_3.h>
 #include <CGAL/draw_face_graph.h>
 #include <CGAL/Random.h>
@@ -45,6 +45,7 @@ void draw(const CGAL_POLY_TYPE& apoly,
 
   if (!cgal_test_suite)
   {
+    CGAL::Qt::init_ogl_context(4,3);
     int argc=2;
     const char* argv[2]={"polyhedron_viewer","--old"};
     QApplication app(argc,const_cast<char**>(argv));
diff --git a/Principal_component_analysis/demo/Principal_component_analysis/MainWindow.cpp b/Principal_component_analysis/demo/Principal_component_analysis/MainWindow.cpp
index 0676b175517..13dde23e2a2 100644
--- a/Principal_component_analysis/demo/Principal_component_analysis/MainWindow.cpp
+++ b/Principal_component_analysis/demo/Principal_component_analysis/MainWindow.cpp
@@ -48,6 +48,7 @@ MainWindow::MainWindow(QWidget* parent)
 
 MainWindow::~MainWindow()
 {
+        m_pViewer->makeCurrent();
         delete ui;
 }
 
diff --git a/Principal_component_analysis/demo/Principal_component_analysis/PCA_demo.cpp b/Principal_component_analysis/demo/Principal_component_analysis/PCA_demo.cpp
index f1b7a78b624..04b8cf11f13 100644
--- a/Principal_component_analysis/demo/Principal_component_analysis/PCA_demo.cpp
+++ b/Principal_component_analysis/demo/Principal_component_analysis/PCA_demo.cpp
@@ -18,9 +18,12 @@
 #include "MainWindow.h"
 #include <QApplication>
 #include <CGAL/Qt/resources.h>
+#include <CGAL/Qt/init_ogl_context.h>
 
 int main(int argc, char **argv)
 {
+  CGAL::Qt::init_ogl_context(2, 1);
+
   QApplication app(argc, argv);
   app.setOrganizationDomain("inria.fr");
   app.setOrganizationName("INRIA");
diff --git a/Principal_component_analysis/demo/Principal_component_analysis/Scene.cpp b/Principal_component_analysis/demo/Principal_component_analysis/Scene.cpp
index e75392cb62d..a4c60dd0a54 100644
--- a/Principal_component_analysis/demo/Principal_component_analysis/Scene.cpp
+++ b/Principal_component_analysis/demo/Principal_component_analysis/Scene.cpp
@@ -28,6 +28,7 @@ Scene::Scene()
 
 Scene::~Scene()
 {
+
     delete m_pPolyhedron;
 }
 
diff --git a/Surface_mesh/include/CGAL/draw_surface_mesh.h b/Surface_mesh/include/CGAL/draw_surface_mesh.h
index f3866938526..c15a7a5028e 100644
--- a/Surface_mesh/include/CGAL/draw_surface_mesh.h
+++ b/Surface_mesh/include/CGAL/draw_surface_mesh.h
@@ -32,6 +32,7 @@ void draw(const SM& asm);
 
 #ifdef CGAL_USE_BASIC_VIEWER
 
+#include <CGAL/Qt/init_ogl_context.h>
 #include <CGAL/Surface_mesh.h>
 #include <CGAL/draw_face_graph.h>
 namespace CGAL
@@ -51,6 +52,7 @@ void draw(const Surface_mesh<K>& amesh,
 
   if (!cgal_test_suite)
   {
+    CGAL::Qt::init_ogl_context(4,3);
     int argc=1;
     const char* argv[2]={"surface_mesh_viewer","\0"};
     QApplication app(argc,const_cast<char**>(argv));
diff --git a/Surface_mesh_topology/include/CGAL/draw_face_graph_with_paths.h b/Surface_mesh_topology/include/CGAL/draw_face_graph_with_paths.h
index 96cad072369..726cf03efd1 100644
--- a/Surface_mesh_topology/include/CGAL/draw_face_graph_with_paths.h
+++ b/Surface_mesh_topology/include/CGAL/draw_face_graph_with_paths.h
@@ -21,6 +21,7 @@
 
 #ifdef CGAL_USE_BASIC_VIEWER
 
+#include <CGAL/Qt/init_ogl_context.h>
 #include <CGAL/Random.h>
 
 namespace CGAL {
@@ -409,6 +410,7 @@ void draw(const Mesh& alcc,
 
   if (!cgal_test_suite)
   {
+    CGAL::Qt::init_ogl_context(4,3);
     int argc=1;
     const char* argv[2]={"lccviewer","\0"};
     QApplication app(argc,const_cast<char**>(argv));
diff --git a/Triangulation_2/include/CGAL/draw_triangulation_2.h b/Triangulation_2/include/CGAL/draw_triangulation_2.h
index 60d15734b2f..fef579d2ff0 100644
--- a/Triangulation_2/include/CGAL/draw_triangulation_2.h
+++ b/Triangulation_2/include/CGAL/draw_triangulation_2.h
@@ -17,6 +17,7 @@
 
 #ifdef CGAL_USE_BASIC_VIEWER
 
+#include <CGAL/Qt/init_ogl_context.h>
 #include <CGAL/Triangulation_2.h>
 #include <CGAL/Random.h>
 
@@ -144,6 +145,7 @@ void draw(const CGAL_T2_TYPE& at2,
 
   if (!cgal_test_suite)
   {
+    CGAL::Qt::init_ogl_context(4,3);
     int argc=1;
     const char* argv[2]={"t2_viewer","\0"};
     QApplication app(argc,const_cast<char**>(argv));
diff --git a/Triangulation_3/demo/Triangulation_3/T3_demo.cpp b/Triangulation_3/demo/Triangulation_3/T3_demo.cpp
index 7b70c57dd07..aef465639ff 100644
--- a/Triangulation_3/demo/Triangulation_3/T3_demo.cpp
+++ b/Triangulation_3/demo/Triangulation_3/T3_demo.cpp
@@ -13,18 +13,17 @@
 
 #include "MainWindow.h"
 #include <QApplication>
+#include <CGAL/Qt/init_ogl_context.h>
 
 int main(int argc, char** argv)
 {
+  CGAL::Qt::init_ogl_context(2, 1);
+
   QApplication app(argc, argv);
 
   app.setOrganizationDomain("inria.fr");
   app.setOrganizationName("INRIA");
   app.setApplicationName("3D Triangulation Demo");
-  //for windows
-#if (QT_VERSION >= QT_VERSION_CHECK(5, 3, 0))
-  app.setAttribute(Qt::AA_UseDesktopOpenGL);
-#endif
 
   MainWindow mw;
   mw.show();
diff --git a/Triangulation_3/include/CGAL/draw_triangulation_3.h b/Triangulation_3/include/CGAL/draw_triangulation_3.h
index 11d25a28f29..0c778ca08a7 100644
--- a/Triangulation_3/include/CGAL/draw_triangulation_3.h
+++ b/Triangulation_3/include/CGAL/draw_triangulation_3.h
@@ -17,6 +17,7 @@
 
 #ifdef CGAL_USE_BASIC_VIEWER
 
+#include <CGAL/Qt/init_ogl_context.h>
 #include <CGAL/Triangulation_3.h>
 #include <CGAL/Random.h>
 
@@ -150,6 +151,7 @@ void draw(const CGAL_T3_TYPE& at3,
 
   if (!cgal_test_suite)
   {
+    CGAL::Qt::init_ogl_context(4,3);
     int argc=1;
     const char* argv[2]={"t3_viewer","\0"};
     QApplication app(argc,const_cast<char**>(argv));
diff --git a/Voronoi_diagram_2/include/CGAL/draw_voronoi_diagram_2.h b/Voronoi_diagram_2/include/CGAL/draw_voronoi_diagram_2.h
index 5e32e12d3d4..66f7d364293 100644
--- a/Voronoi_diagram_2/include/CGAL/draw_voronoi_diagram_2.h
+++ b/Voronoi_diagram_2/include/CGAL/draw_voronoi_diagram_2.h
@@ -17,6 +17,7 @@
 
 #ifdef CGAL_USE_BASIC_VIEWER
 
+#include <CGAL/Qt/init_ogl_context.h>
 #include <CGAL/Random.h>
 #include <CGAL/Triangulation_utils_2.h>
 #include <CGAL/Voronoi_diagram_2/Face.h>
@@ -316,6 +317,7 @@ void draw(const CGAL_VORONOI_TYPE &av2,
 #endif
 
   if (!cgal_test_suite) {
+    CGAL::Qt::init_ogl_context(4,3);
     int argc = 1;
     const char *argv[2] = {"voronoi_2_viewer", "\0"};
     QApplication app(argc, const_cast<char **>(argv));