diff --git a/Arrangement_on_surface_2/demo/earth/CMakeLists.txt b/Arrangement_on_surface_2/demo/earth/CMakeLists.txt
index 3760a72aace..fbcb7351955 100644
--- a/Arrangement_on_surface_2/demo/earth/CMakeLists.txt
+++ b/Arrangement_on_surface_2/demo/earth/CMakeLists.txt
@@ -77,7 +77,7 @@ source_group( "Graphics"  FILES ${source_files_graphics} )
 # GRAPHICS-GEOMETRY (Graphics-related)
 file(GLOB source_files_graphics_geometry
   Line_strips.h             Line_strips.cpp
-  SingleVertex.h            SingleVertex.cpp
+  Single_vertex.h           Single_vertex.cpp
   Sphere.h                  Sphere.cpp
   Triangles.h               Triangles.cpp
   Vertices.h                Vertices.cpp
diff --git a/Arrangement_on_surface_2/demo/earth/Main_widget.cpp b/Arrangement_on_surface_2/demo/earth/Main_widget.cpp
index ecbbd4b29c4..ddb44b76ef0 100644
--- a/Arrangement_on_surface_2/demo/earth/Main_widget.cpp
+++ b/Arrangement_on_surface_2/demo/earth/Main_widget.cpp
@@ -37,6 +37,10 @@ Main_widget::~Main_widget()
   doneCurrent();
 }
 
+void Main_widget::set_mouse_pos(const QVector3D mouse_pos)
+{
+  m_gr_mouse_vertex->set_pos(mouse_pos);
+}
 void Main_widget::hightlight_country(const std::string& country_name)
 {
     static std::string  prev_picked_country;
@@ -102,8 +106,8 @@ void Main_widget::initializeGL()
 {
   m_pick_handler = std::make_unique<GUI_country_pick_handler>(*this);
 
-  m_mouse_pos = QVector3D(0, -1, 0);
-  m_gr_mouse_vertex = std::make_unique<SingleVertex>(m_mouse_pos);
+  QVector3D initial_mouse_pos(0, -1, 0);
+  m_gr_mouse_vertex = std::make_unique<Single_vertex>(initial_mouse_pos);
 
   // triangulation
   {
@@ -386,7 +390,7 @@ void Main_widget::paintGL()
       //auto pos = m_mouse_vertex->get_pos();
       //pos.setX(pos.x() + 0.01);
       //m_mouse_vertex->set_pos(pos);
-      m_gr_mouse_vertex->set_pos(m_mouse_pos);
+      //m_gr_mouse_vertex->set_pos(m_mouse_pos);
       draw_safe(m_gr_mouse_vertex);
     }
 
diff --git a/Arrangement_on_surface_2/demo/earth/Main_widget.h b/Arrangement_on_surface_2/demo/earth/Main_widget.h
index e13aa5adfd9..3e958926813 100644
--- a/Arrangement_on_surface_2/demo/earth/Main_widget.h
+++ b/Arrangement_on_surface_2/demo/earth/Main_widget.h
@@ -29,7 +29,7 @@
 #include "Kml_reader.h"
 #include "Line_strips.h"
 #include "Shader_program.h"
-#include "SingleVertex.h"
+#include "Single_vertex.h"
 #include "Sphere.h"
 #include "Triangles.h"
 #include "Vertices.h"
@@ -49,7 +49,7 @@ class Main_widget : public QOpenGLWidget, protected OpenGLFunctionsBase
   auto& get_model_matrix() { return m_model; }
   auto& get_arr_handle() { return m_arrh; }
 
-  void set_mouse_pos(const QVector3D mouse_pos) { m_mouse_pos = mouse_pos; }
+  void set_mouse_pos(const QVector3D mouse_pos);
 
   void hightlight_country(const std::string& country_name);
 
@@ -92,8 +92,7 @@ class Main_widget : public QOpenGLWidget, protected OpenGLFunctionsBase
   std::unique_ptr<GUI_event_handler> m_pick_handler;  
 
   // These are used to highlight the picked position by right-mouse click
-  QVector3D                         m_mouse_pos;
-  std::unique_ptr<SingleVertex>     m_gr_mouse_vertex;
+  std::unique_ptr<Single_vertex>  m_gr_mouse_vertex;
 
 
   // TRIANGLES for rendering the countries in solid
diff --git a/Arrangement_on_surface_2/demo/earth/SingleVertex.cpp b/Arrangement_on_surface_2/demo/earth/Single_vertex.cpp
similarity index 67%
rename from Arrangement_on_surface_2/demo/earth/SingleVertex.cpp
rename to Arrangement_on_surface_2/demo/earth/Single_vertex.cpp
index 439af35bc12..2793f175ae4 100644
--- a/Arrangement_on_surface_2/demo/earth/SingleVertex.cpp
+++ b/Arrangement_on_surface_2/demo/earth/Single_vertex.cpp
@@ -7,10 +7,10 @@
 //
 // Author(s): Engin Deniz Diktas <denizdiktas@gmail.com>
 
-#include "SingleVertex.h"
+#include "Single_vertex.h"
 
 
-SingleVertex::SingleVertex(const QVector3D& pos)
+Single_vertex::Single_vertex(const QVector3D& pos)
 {
   initializeOpenGLFunctions();
 
@@ -47,35 +47,40 @@ SingleVertex::SingleVertex(const QVector3D& pos)
 }
 
 
-void SingleVertex::set_visible(bool flag)
+void Single_vertex::set_visible(bool flag)
 {
   m_visible = flag;
 }
-void SingleVertex::set_pos(const QVector3D& pos)
+void Single_vertex::set_pos(const QVector3D& pos)
 {
   m_pos = pos;
-  glBindBuffer(GL_ARRAY_BUFFER, m_vbo);
-  auto vertex_buffer_size = sizeof(m_pos);
-  auto vertex_buffer_data = reinterpret_cast<const void*>(&m_pos);
-  auto offset = 0;
-  glBufferSubData(GL_ARRAY_BUFFER, 
-                  offset,
-                  vertex_buffer_size,
-                  vertex_buffer_data);
+  m_update = true;
 }
-const QVector3D& SingleVertex::get_pos() const
+const QVector3D& Single_vertex::get_pos() const
 {
   return m_pos;
 }
 
 
-void SingleVertex::draw()
+void Single_vertex::draw()
 {
   if (m_visible)
   {
+    if (m_update)
+    {
+      glBindBuffer(GL_ARRAY_BUFFER, m_vbo);
+      auto vertex_buffer_size = sizeof(m_pos);
+      auto vertex_buffer_data = reinterpret_cast<const void*>(&m_pos);
+      auto offset = 0;
+      glBufferSubData(GL_ARRAY_BUFFER,
+                      offset,
+                      vertex_buffer_size,
+                      vertex_buffer_data);
+      m_update = false;
+    }
+
     glBindVertexArray(m_vao);
       glDrawArrays(GL_POINTS, 0, 1);
     glBindVertexArray(0);
   }
 }
-
diff --git a/Arrangement_on_surface_2/demo/earth/SingleVertex.h b/Arrangement_on_surface_2/demo/earth/Single_vertex.h
similarity index 78%
rename from Arrangement_on_surface_2/demo/earth/SingleVertex.h
rename to Arrangement_on_surface_2/demo/earth/Single_vertex.h
index c64e4167d63..5c6f7da576d 100644
--- a/Arrangement_on_surface_2/demo/earth/SingleVertex.h
+++ b/Arrangement_on_surface_2/demo/earth/Single_vertex.h
@@ -15,10 +15,10 @@
 #include "Common_defs.h"
 
 
-class SingleVertex : protected OpenGLFunctionsBase
+class Single_vertex : protected OpenGLFunctionsBase
 {
 public:
-  SingleVertex(const QVector3D& pos);
+  Single_vertex(const QVector3D& pos);
 
   void set_visible(bool flag);
   void set_pos(const QVector3D& pos);
@@ -28,6 +28,7 @@ class SingleVertex : protected OpenGLFunctionsBase
 
 private:
   bool      m_visible;
+  bool      m_update = true; // flag to update the VBO (set_pos sets this)
   GLuint    m_vao, m_vbo;
   QVector3D m_pos;
 };