After drawing quad or polygon and resizing entire viewport is the color of the quad/poly

if (!loaded)
                return;
 
            List<Pixels> tempPoints = new List<Pixels>();
            tempPoints.Add(new Pixels(300, 50));
            tempPoints.Add(new Pixels(200, 200));
            tempPoints.Add(new Pixels(250, 150));
            tempPoints.Add(new Pixels(100, 100));
 
            reference = tempPoints[0];
            tempPoints.Sort(new Comparison<Pixels>(MapUtils.SortPointsClockwise));
 
            //  Fetch the map bounds
            MapUtils.GetMapBounds(ref mapBounds, Program.main.glControl1.Width, Program.main.glControl1.Height);
 
            //  Clear the OpenGL control
            GL.Clear(ClearBufferMask.ColorBufferBit | ClearBufferMask.DepthBufferBit);
 
            //  Enable 2D texturing and blending
            GL.Enable(EnableCap.Texture2D);
            GL.Enable(EnableCap.Blend);
 
            //  Set the hint
            GL.Hint(HintTarget.PerspectiveCorrectionHint, HintMode.Nicest);
 
            //  Fetch displayed tiles
            MapUtils.FetchTiles();
 
            ////  Draw Rectangle
            GL.MatrixMode(MatrixMode.Modelview);
            GL.Color4(0.0, 0.0, 1.0, 0.5);
            GL.BlendFunc(BlendingFactorSrc.OneMinusConstantAlpha, BlendingFactorDest.SrcAlpha);
            ////GL.Color3(Color.Blue);
 
            GL.Begin(BeginMode.Polygon);
            //GL.Vertex3(200, 200, 0);
            //GL.Vertex3(100, 100, 0);
            //GL.Vertex3(300, 50, 0);
            //GL.Vertex3(250, 150, 0);       
            foreach (Pixels point in tempPoints)
            {
                GL.Vertex3(point.X, point.Y, 0);
            }
            GL.End();
 
            //  Flush the buffer
            GL.Flush();
            //  Swap the buffers
            glControl1.SwapBuffers();