drawing VTK point on the real time : i'd like to draw a Point using VTK library on the real time.
i have a little problem on doing this. my program is drawing the point on the  but i can't see them until i click on my windows control.

here is my code:

     private void Pointdessinateur()
        {

            // Create the geometry of the points (the coordinate)
            vtkPoints points = vtkPoints.New();
       
            List<double> X = new List<double>(); // création de la liste
            List<double> Y = new List<double>();
            List<double> Z = new List<double>();
            // Create topology of the points (a vertex per point)
            vtkCellArray vertices = vtkCellArray.New();
            int i = 0;
            
                    X.Add(XCnorm);
                    Y.Add(YCnorm);
                    Z.Add(ZCnorm);
                    
            int[] ids = new int[X.Count];
            for (i = 0; i < X.Count; i++)
                ids[i] = points.InsertNextPoint(X[i], Y[i], Z[i]);

            int size = Marshal.SizeOf(typeof(int)) * X.Count;
            IntPtr pIds = Marshal.AllocHGlobal(size);
            Marshal.Copy(ids, 0, pIds, X.Count);
            vertices.InsertNextCell(X.Count, pIds);
            Marshal.FreeHGlobal(pIds);

            // Create a polydata object
            vtkPolyData pointPoly = vtkPolyData.New();

            // Set the points and vertices we created as the geometry and topology of the polydata
            pointPoly.SetPoints(points);
            pointPoly.SetVerts(vertices);

            // Visualize
            vtkPolyDataMapper mapper = vtkPolyDataMapper.New();
            mapper.SetInput(pointPoly);
            vtkActor actor = vtkActor.New();
            actor.SetMapper(mapper);
            actor.GetProperty().SetPointSize(3);
            actor.GetProperty().SetColor(0.25, 0.0, 0.0);
            vtkRenderWindow renderWindow = renderWindowControl1.RenderWindow;
            vtkRenderer renderer = renderWindow.GetRenderers().GetFirstRenderer();
            renderer.AddActor(actor); 
        }